You nailed it. I learned from a very knowledgeable and reliable source that it's all related to their TPI design, which is exactly why they're tossing it. He straight up told me not to buy a TPI bike. He said even getting them properly set up to race (or even ride enjoyably for that matter) cost a fortune, having to buy a new tunable ECU and also upgrade the trash suspension they're now using. He said around $1.5k~$2k is what it cost to make things right and reliable.
I took his advice come time to replace my 2013 350 by going with another 350. I was however still faced with having to upgrade the trash suspension.
I always think about the difference in purchase price between a KTHusky and a Yamaha, and then think about just getting a 315 built for a YZ250FX with part of the difference. Or a lower-effort, cheaper big bore or bore/stroke and head work.