These are all good points. 1) Anecdotally, round numbers feel more "honest" to me, it's probably been studied but I can't find any references. 2/3) Definitely

These are all good points. 1) Anecdotally, round numbers feel more "honest" to me, it's probably been studied but I can't find any references. 2/3) Definitely reviews themselves are the most valuable and if you can find a way to increase their supply, you've got something really worth selling. 4) Potentially a good idea but could turn some people away. Maybe a throttle rather than a hard limit. What about a ladder like this to get reviews in the bank? 1 gets you your first 1 2 & 3 get you your second 4 & 5 & 6 get your third etc