Yes. The annual subscription is < $250/year, so I don't believe it's expensive enough to stop people purely because it's a big charge.
>How is the distribution of vintages of your user base?
My startup is fairly new (12-18 months old), so I don't have much insight into such statistics. However, I will note that growth has somewhat stagnated (<4% MRR growth every month). While I'm not looking to grow rapidly and I don't have any external pressure to grow (no VCs :)), perhaps the stagnation is a good motivation to introduce segmentation, higher prices, etc.
>it’s almost always a good idea to do it without disrupting (too much) your existing user base.
Absolutely. I always grandfather existing users and I have a few dozen very early users who are paying peanuts compared to the current pricing. I value their super early feedback a lot in shaping my startup, so I'm happy to grandfather their subscriptions forever. I even get emails every now and then from some early users asking if I could "upgrade" them to the current, higher pricing!