So as not to hijack another thread ...
Freds answer to my interpolation question was

"To the best of my knowledge, the interpolator (Fusion, Hybrid, Pyramid) isn't a factor until you go to print to paper, print to File, ot upsize or downsize an image
You aren't seeing an interpolated image in Full Page Editor; but a High Def image or a low rez image, depending on your selection".

If a print will be affected by the 'flavor' of interpolation one uses and the differences cannot be seen in soft proofing prior to printing, why then do most of the gurus at Luminous Landscape put so much stress on soft proofing even though you still really need to print to see the true results on edits and interpolation??
 
Fred...
I figured out that instead of cutting small pieces off the 24" rolls for tests I can simply rewind and reload the roll paper and relocate the second, third, or forth test print manually on the existing section of paper I'm using, by turning auto cutting off.

As always, thanks for your input!
David

I have to comment or Terry will get more posts than I.
Terry said it all, and he is being tactful.
I want to comment on Gurus.    Gurus are over rated to say the least.
I have one guru. Mike Chaney. I have been listening to and learning from Mike for about 11+ years. I have seen Mike challenge plenty of misinformed gurus on DPreview.
I have never been steered wrong by Mike. Check out his articles posted here on many many topics including Soft Proof.

http://ddisoftware.com/tech/articles/september-2005-soft-proofing-basics/

As you see, as you read through, Mike is not a guru that gives much weight to Softproofing. 

Just some observations.
Fred

David,
It's time to take a  deep breath!

Let's break this down and simplify,
PPI stands for pixels per inch.
This is input resolution of the image to be printed, and depends on the setting in the driver that controls input requirement and the resolution of image.

If the image has a resolution of 2000 x 1600, and you are going to print a 10 x 8 size, then the ppi becomes 200 ppi.
If you have fine detail checked on the larger printers or Best Photo selected on the 13" wide or smaller Epsons' drivers then you will see 720 ppi in the resolution box in Qimage, as long as you have it set to the default; MAX
Qimage will interpolate your 200ppi image to 720 ppi so it will have the best data sent to the printer.

The FUSION, HYBRID, BICUBIC, etc, refers to the quality of the interpolator. Use the Fusion. It is the best for printing pictures.
So Fusion will interpolate the 200 ppi to 720 ppi.
That took care of the input side.



Output side!

DPI!   DPI means DOTS PER INCH.
That is different from ppi.   DPI refers to the spray of ink per inch.
Again, a few factors will come into play. Your settings in the driver, again, are what tells the printer what you want.
You are seeing also that you have choices.
You can select 2880 x 1440 by selecting Max quality; 1440 x 720 by selecting Quality.
Printers also tout droplet size in picoliters.... that is part of the equation for nozzle spray; out of the user's purview. I mention it only because you will see that term in print and wonder.


Not so!   You can see above that setting the driver to Fine detail will inform QU that you are going to use 720 ppi as an input ppi, and it will show 720 ppi.


Ok what does it all mean?
Always use the correct profile that is recommended by the PAPER manufacturer for your printer.
Yes, there are different profiles for 1440 DPI and 2880 dpi.
I have the same thing for my Epson Prem. Glossy paper for my R 1800 Epson.
If you get some paper to use for which there is no profile offered, then I would use Let Printer Manage color.
(I bought a few hundred sheets of HP Advanced Photo Paper Glossy. A really nice (not too thick) paper for DVD covers and give -a-way prints. There's no profile for the paper or my printer.
I experimented with paper selection and found it worked best with Prem Glossy selected and Let Printer Manage Color)

What settings work best for you? I would use "Quality" and make a test print of something with a lot of detail. Then "Max Quality". Shoot a tree trunk or something with a lot of fine detail. Compare the prints. Can you see a difference? Use a magnifier. Can you see a difference?  
Make another test. Try a print made from 100 ppi input. Same as above; "Quality" 1440 DPI and "Max Quality" 2880. Can you see a difference.

Depending on the size print and how far away on stands to view the print, 360 ppi might look the same as 720 ppi.   Again, make your tests.

The largest prints I can make are 13 x 19"  I use 720ppi input (all the time) and 1440 DPI output.
My experiments showed that I needed a magnifier on a tree trunk plus asking my wife, (AKA Eagle Eye) to see 2880 DPI output.

I have a friend Carmen, who is a pro photog and teacher of photography.   I go to his place and help him set up his preset printer setups for various job sets. He always uses 360 ppi input and 1440 output, and makes very large gorgeous prints on a 9880 Epson.

High Speed?
Printer sprays ink when the head is moving from left to right, and stops when the head goes back for another run. That is High speed unchecked.
Check High Speed, and the printer sprays ink left to right, and right to left also.
Theoretically, High Speed off, is better. If you can see a difference, let us all know. I cannot.
On the other hand, you bought a very sophisticated high quality printer. By inference, you want the best quality. If the paper people say run it with High Speed unchecked, I would.
You should be set up the same way they were set up when they printed their target to make the profile.

I hope I answered some of your concerns.
If I didn't do too well explaining, that's my fault, so feel free to pick away.
Oh, and lay off the softproof. The Rehab center for ex- Photo Shop people is filled up with members weaning off of Softproof.
Make a print and you will know.  
Fred

David,
I was going to use that line; paraphrased, "We don't need no steenkin Softproof", but I didn't think many people would get the humor or remember the movie it came from.
Treasure of Sierra Madre!  (1948, for all you iphone, blue toothers who text all day).
Thanks for the good sense of humor.

Fred