I think, you get hit with price increases no matter who you are with.
I also switched to TD/Primmum, as I found for my bike and myself, they were the cheapest.
However, it's not just how much you pay, but how well it goes, if you actually have to use your insurance, like I had to, last year, when someone totalled my last bike (ran a stop sign).
I found TD, handled the claim well, with one exception...I had to dicker back and forth with them, quite a bit, for them to offer a reasonable replacment value for the bike. They really tried to low-ball on the replacement cost. I'm sure they all do that though.