I have only been on road bikes / did few crit races. How is leadville / sea otter etc?? I watch those races on YouTube and thought bout it but seems like I’d have to switch up bikes completely for it // prep for totally different level of racing
this may be the next goal!
You do need a Mountain Bike. Unless you're a really, really competent MTB'er don't believe anyone who tells you they're not technical, not MTB races, and more gravel races. That's not to say that you can do them perfectly safely coming from Road / Crit (plenty of people do), but the big descents especially deserve your respect, and you'll be more comfortable and faster on a full suspension XC Bike. Training is training, but you'll want to spend time on dirt getting to be a better bike handler. (Plus, Mountain Bikes are fun!)
If you're doing it for fun, run what you brung.
You're too late for Leadville this year unless you find a charity / fundraising spot. And, it's tough to get into regardless. But, plenty of other great XC and Gravel Races / Events across the country. If I had to pick one bike, I'd get rid of Road and Gravel and Keep the XC, it's surprisingly capable with fast tires.
Some Leadville stoke For you for a little look at the PowerLine Descent, and then the Singletrack with some views of the mountains:
If you decide to head that way, shoot me a message, happy to help.