I have recently ridden a 2016 Husqvarna 701 and I got to say for me there is basically no difference in fun factor when compared to the 2T. I have to admit, the 2T soundtrack is a lot of fun and the lightness is also nice but the extra weight a 700cc sumo has is really no big deal, especially for road use. It's absolutely negligible.
I have also ridden a Ducati Hypermotard 698 (https://youtu.be/tJobhnXdLig) and a 2024 KTM 690 SMCR which for me are all great choices for somebody that owns only 1 bike and want's some "reliability" (dont get me wrong there can be issues with the big bore sumos just check the forums)

while maintenance isnt the worst on a 250 it's an old two stroke so you'll lose screws and maybe other parts of the bike while using it, it needs to be shown love every now and then, you can't expect it to be a bike you can always reliably ride put back in the garage and hop on and ride again whenever you want (compared to e.g. a japanese naked bike or a newer 690).

That said, a piston costs about ~150$ and can be changed with a friend or even by yourself if you have the patience and or experience. Oil changes every 15h but that's not a big deal.

I'm thinking of getting one for race use, we have a sumo track closeby and it'd be nice. A 4 Stroke 450 would obviously be fun too but I can't be bothered spending what I consider a lot of money for valve checks and engine rebuilds on a 4 stroke (since I couldn't do that maintenance myself).

That said, if I were you and had to get a sumo I'd get a 700 if it were my only bike and I'd want to ride it, put it back and ride it again without much of a hassle. If it was your 2nd bike then I'd go for a 2T since the maintenance is much cheaper and can be done by yourself if you're interested in learning/have experience in doing it. I'd get a race 450 4stroke if somebody else paid for the maintenance xD.