Cartridges are always going to be in flux, so that, and tubes in your case, don't count. I truly am happy with everything, of course, as mentioned the option of adding a power amp is in the clouds, as a far off maybe or if a stellar deal comes along. The only other piece I'd even consider a move to would be the Manley Oasis, but that's not happening any day soon only because I'm sure used and discounted Chinooks are going to flood the market right now, so getting a good price, or at least what I'd like to get for it, is probably unrealistic at the moment. That said, that move is more about creature comforts, like not having to open the chassis to make changes, more than a question of "quality", the Chinook still rocks.
Looking at new gear is always fun, and as I said, it's a gas watching what other do, hear their experiences, but that proverbial "line in the sand" is there for me and it'll take a lot to cross it now a days