I am certainly not going to try to talk you out of it. I have been pleased with my 2018 machine I purchased in March, and have about 225 miles on it so far. If you have read what various owners have posted on this forum over the past several years, you'll have a pretty good idea of what to expect from the machine.
As far as competition, I agree with you that the Pioneer is not truly comparable in features. Honestly, about the only other machine you are going to consider is the Polaris Ranger 500, and lately I have seen some that appear to be priced within a reasonable ballpark of the KYMCO. Considering how many thousands, or tens of thousands, more Rangers there are out there, and their proven reputation, this is something at least worth considering.
That said, if you are getting a good deal on the KYMCO, you can't go wrong. If you are buying a leftover 2018 model at this point, you definitely shouldn't be spending more than $7,500 on the machine, considering you can get yourself a brand new 2019 for $7,999. Heck, I'd say you can probably get it for $7,200 or $7,300 if you haggle a bit. I would think at this point the dealer is going to be glad to see it move and make room for more new inventory.
Final word of caution is regarding the extended warranty promotion, if that's still going. When I bought, KYMCO was offering a free, 36-month extended warranty on top of the 12-month factory warranty. I did receive confirmation from KYMCO that my machine was registered properly for warranty and that I would receive the extended warranty information from the third-party vendor that administers it in 45-60 days. Well, I am not at about 90 days past purchase and still nothing on the extended warranty. I sent off another email to KYMCO about this yesterday but heard nothing. I think my next step will be to contact me dealer and see if they can reach out to KYMCO and get this squared away. It's not like I have had any problems with the machine, but hey, we are talking about free coverage from 2020-2022, so I definitely don't want to let that slip away!
If you ultimately decide to purchase the KYMCO, please let us know. We always appreciate a few photos and first impressions from new owners. Good luck!