The experts can correct me if I'm wrong, but from what I understand and what I've seen, you're going to be limited to right around 100HP/120TQ, maybe a little more with the 255's regardless of the other work you do. It just seems like that is where those cams top out. That is totally fine depending on your goals. The other work however can offer benefits other than power, which a couple of the others have described. Quieter operation, longevity, etc.
I went with the Cycle-Rama 575's and gained everywhere across the board, but also had a bump in compression to about 10.2 to 1. It is a pretty common bolt it cam for 103's and 110's both. For what it's designed for, I think the 255 gets the job done. Especially with solid stage 1 components and a good tune. You may be covered there.
By the looks of your post, it seems like you're more into a solid running, dependable bike rather than power chasing. I can respect that!