No prob

Both those locos can handle down to 11"ish radius, though it doesn't look good.

16" should be no problem.

C55 is no problem.
(And looks much, much better than C80)

The trick with ME track is getting smooth curves: ME track is very stiff and retains any bend (unlike Atlas flex which "returns" to normal straight), so it's very easy to have little wiggles in the curve.

On the other hand, ME, once bent into a curve, keeps that curve and you can easily test cars through it before caulking it down.

So lay out smooth flextrack and build your turnouts correctly and you should have no problems.
(If you're using a Fast Tracks jig then I've found that the guard rails and wing rails can be a little close to the stock rails and frog and thus pinch wheels, so if that happens after you've made sure your wheels are in gauge, reheat those rails and pull them slightly farther away and everything will run fine).

2-8-2

My Kato Mikado handles 16" with no problems on either 55 or 80. Much tighter and the pilot wheels like to hop off the track.  Layout your radius carefully, or use a template.

john