I have spent a lot of time trying to optimise the V700 to get the best out if it. For what it's worth, these are my observations:
For 6x7 transparencies, I've done side by side comparisons for 12"x16" prints scanned by me and uploaded to a pro-lab with those scanned and printed by the pro-lab and I can see no real differences at normal viewing distances. There might be a very slight difference close-up but it's marginal. Conclusion: The V700 gives me all the resolution for 6x7 that I need.
For 35mm I've done the same. Scanned the transparency and uploaded to a pro-lab and got them to scan and print, again to 12"x16". There is a very real difference, the pro-lab version is way better. However, this is only noticable in a side-by-side comparison. If you had the self-scanned and pro-lab printed one on your wall, it would be good, not totally perfect, but good. To be fair, a 12"x16" print from 35mm is really pushing it anyway.
My other observations are:
Epson software vs silverfast - makes no difference. Silverfast is more flexible to get what you want, but the final scan with both once you've tweaked them is the same.
Ice - on quality setting there is a very slight loss of sharpness, but this is very very small, and the effort it saves later in getting rid of dust spots is well worth it.
6400 vs 3200 dpi - I've compared 6400 dpi which I've down sampled to 3200 with a direct 3200 dpi scan and there is no difference at all. 3200 scans are much faster.
Holder-height - does have an effect. Mine seem to be best at the '+' setting. However, getting the transparency strip in right makes a big difference too. Scan it once, take it out, put it back and scans can be very different in sharpness. I may try the anti-newton glass insert from betterscanning.com to be more consistent. This is not an issue with mounted 35mm transparencies.
Scans need quite a lot of unsharp mask afterwards, more than I would normally feel comfortable with. In Cpature NX2, about a 70% intensity, 5% radius and 0% threshold seems about right. Looks bad on screen but prints well (when uploaded to the lab anyway, I don't do inkjets).
I may spend a bit of time with the V700 before looking to other options, at least until I can find some good sample images with the Plustek for 35mm.