Hi, I can recall some earlier
experience with the very first two MD 500E equipped with such engine some 20 years ago.
I was a fresh pilot and flown until there with the usual C20B.
A the first glance I didn't notice any difference, but at some 750 C T.O.T. suddendly I remarked that the gage "frosted" but as you mention, the TQ raised!
We performed many flights with both ships and any pilots made the same finding.
But after some 50 Hrs we began to experience engine chips, firstly on the first ship, then on the other too.....
Allison representative took after a meeting some corrections, and after them both ships never experienced any troubles more.
Fuel consuption was slightly more than a 20B.
That's about the MD 500; so I would recommend it.
On the 206 its look a little bit other; two companies in competition were owning two B3 one with the C 20J and the other with the C 20R.
After a perfectly "adjusted" and polished MR leading edge
, the first one performed by far better than the "more powerful"!
So I hope that my small experience may give you some help.
Wish all the best
