I race the local harescrambles on my wr250r, it does alright unless the track is fast and sandy then the more powerfull bikes pull away from me.
They bumped me up to intermediate last year since I was 3rd overall the year before in the novice class and I skipped a race, but I was on a gasgas that year.
I was mid to back of the pack as an intermediate last year but I can/could win in the novice class, the bikes not to blame at all, thats how fast I go on any bike, im as strong as an oxe but not in that good of shape, I get tired if I go flat out for 1 1/2 hours and need to pace myself so I can finish lol.
One race a guy showed up on a supermoto wr250x with 17 inch knobbies and got 3rd in the intermediate class, the bike is capible if you are! This guy now has a mx bike and is close to winning every race now, its 90% rider 10% bike.
I say sign up in one of the easier classes and go for it, its a ton of fun.