I'm a tenant. If my landlord tried to raise the rent more than I considered reasonable, I'm not going to discuss, I'd just move. In fact, I did move last time. and I'm one of the tenants you want.
Make sure you know what the true market rate is and use that as a guide.
+1
I moved over about that same rent increase. We too, had a rent around 1700 I think, and the increase was going to be $75 or 100. We did make an effort to write a letter, got a no response so we moved. If we had been told $50, we might have stayed. In the future, I'd probably just move w/o writing the letter (although I own now). We figured we had two years left in that city (I was in grad school) and they were likely to raise it again the next year when we'd have even less incentive to move. We also felt that size increase was unwarranted by the market, particularly as a restaurant was going in downstairs in the building over, increasing noise for us. To avoid it happening again, we signed a 22 month lease at the next place. The move cost us $800 and we found a smaller but cheaper place by $100 I think, in a better location, so probably saved $3000 or $1500 each.
Did the property manager give a reason for the suggested rate increase?
If you like the tenants, they pay on time and are reasonable, don't raise by that sum.