Have you actually scanned any of your mags for other people to download? The problem with most of these projects is the ones that are so enthusiastic to read the scans often are not prepared to scan what they own, and therefore the scanning ends up being done by only a few people.
I'm sure PeanutUK wouldn't mind if you scanned some of your AP's so he could put them online...
As for SPS images, apart from the fact they are write only, 99% of coverdisks have no protection so ADF's are just as good and are far easier for real Amiga owners to use. But SPS for the protected coverdisks is a good idea imho.