The main difference between the ix and fi series is the durability. The consumables will last longer on the fi series, but otherwise it's hard to tell the difference between the scans.
Dust lines are a big nuisance and completely normal. I wipe down the glass between every magazine or sometimes more often. I also spot check the scans as they get saved in case their are dust lines and I have to wipe the scanner and start again. As annoying as it can be some days, it's an easy trade off I am willing to make for the speed over scanning with a flatbed.
For Photoshop processing, I've attached two Photoshop Actions to this post. One is for my fi-7160 using ScanSnap Manager, and the other is the one I would use for Phillyman's scans as he has an ix500. You can use either as a starting off point to tweak the settings to your liking, assuming your scans come out the same as ours. I only adjust the Brightness/Contrast, Levels, and Hue/Saturation; you may feel you want to tweak more settings.
ScanSnap Manager.atn
Magazine - Phillyman.atn