Well, in terms of its effect on flash memory, then no, it has no plausible negative consequences.
But! Remember that each time you screw it up and need to re-flash, you're only increasing your odds that one of these days it will actually become bricked and not be able to get into a re-flashable state (although from what I've seen this is very, very rare).
A restore is basically just a whole bunch of read/writes. Most flash drives(ipod tough has one) only have so many writes to them. However they are usually un the hundreds of thousands. You would have to move alot of data on the touch and restore it alot. chances are however that the ipod will break before the flash wears out.