New Bike advice/guidance

I'm newish / beginner-ish 49 y/o (5'11", 155lbs) dirt bike rider that's looking to purchase my first bike.  To get myself started on riding, I had roughly 25 hours of training on a pit bike from a pro SX/MX rider on his home tracks.  I then went to Austin to get an additional 15 hours of coaching on both a crf125 and a klx230r.  My current plan is to do a mix of track and trail riding.  I was initially set to purchase the klx but was worried that I would potentially outgrow the bike in a year or less.  So now I'm looking at the YZ250FX, CRF250RX and KX250X.  I realize that these are much more powerful and aggressive trail racing bikes.  However, I was hoping that if I used the bikes with the "mellow" map settings that I'd be able to manage the power as I continue to learn.  I was just hoping to get some guidance on which of the 3 bikes above might be a little more manageable by a rider with my limited experience.  For what it is worth, I plan to continue to train this year with various professional coaches.  Thank you in advance for the help!