Your concern is should not be so much if you are able to get a good interest rate, although this is one small thing you should be concerned about, you should be more concerned about how long your loan offers are sitting in the lending book, because this is time when you receive no interest.

I would also point out to you that it is expected that a number of forks are expected to take place on the Bitcoin blockchain within the next couple of months, and poloniex has publicly stated they will not give credit for the 'forked' coins to lenders, so it would be il-
advised to keep your BTC on poloniex past late July.