My question is this: Would the Donek Incline be a suitable board for
me as a
relative beginner?
I'd say that if you can confidently turn on both sides while going
down a steepish blue run, then you'll be fine.

Agreed. The board will encourage you to make crisp, carved turns, as
opposed to slide-turns, helping you accomplish your goal of "making
better turns".

FWIW my wife's cousin borrowed my old Incline 160 while he was visiting
us after riding 4 or 5 times on rental equipment. He rode it with us
for 2 days, enjoyed it a lot, and markedly improved his riding skills.
I sent him home with it, since I was riding my Wide 161 most of the time
anyways!

Mike T