I want an ATV but I’ve never ridden one and am conflicted about what to get. I live near an MX track but also near mellow mt fire roads. How fun are Grizzly’s on an MX track?

Here is some pertinent data:
No hunting or mudding or hauling.
I like speed but I’m 64 so somewhat cautious.
Home base is Truckee, CA., and I’ll ride from 5000′ to 7000.
Sport ATV’s look much more fun to me than the 4×4 options but the softer ride of IRS is appealing too.
Although I have never ridden an ATV, I have some skills. I’ve owned and off-roaded an old VW dune buggy. Owned a couple of street motorcycles, I mountain bike every other day. Snow ski every day in the winter. Kitesurf regularly in surf. But now I am board and want to try something new.

The 2wd IRS options are limited to a troublesome Polaris Outlaw and a too powerful Honda TRX 700xx. My favorite other option is a Grizzly 700 because of the EFI and EPS but they seem overly specialized for steep and rocky or wet terrain and not good enough for Mx and maybe not as fun on fire roads. There seems to be no good tweener option.

What should I get?

Thanks!
Doug