With price boosts, I tend to find that the lay odds are still higher anyway. I guess some bookies are more competitive with their boosts than others. So I tend not to bother!
I had an issue with an unmatched Smarkets bet today, even though there was plenty of liquidity in the market. I read the Smarkets help files and it turns out that if the odds change (they went up in my case) you're kind of screwed. Not only that, but they went and cancelled the unmatched portion of the bet as soon as the match kicked off - since it was football and you can bet in-play, I figured there was still a chance of completing the match. Nope!
Anyway, I went to the Tricky Bet website and calculated how much I'd need to lay at Betfair to cover myself, so it worked out OK. I still feel cheated by Smarkets though! I'm sure Betfair will still complete an unmatched bet even if the odds change?