Not trying to be rude by asking this, but how much faster is a purpose-built XC bike going to make you in an XC race? And that isn’t directed just as YOU, I’m asking how much time the bike actually shaves per mile, with identical effort.
Sounds to me like you’re definitely due for an upgrade, but I question how many riders (I have this debate with myself a lot) can really race faster on a XC bike versus a good (and probably more comfortable) trail bike.
A friend of mine is a serious cat 1 racer. He rides his fat tire bike on the trails… the race bikes are (almost) only for racing. Maybe I misunderstood, and you’re fine with that, but I don’t have the budget to spend the most money on the bike I will likely ride the least often. It would also suck to see your primary bike end up being faster, but less comfortable than it could be – especially if it’s only marginally faster.