I am pretty much trying to talk myself into just what you outlined. The diameter on my stab LE is normally about 1/8" on a 3/8" thick stab. If I keep that and do a nice parabolic curve back to about 1" I have just saved a day of grief trying to get the planking on a double taper without warping it. The elevator is not a problem. I use a straight taper from 3/8" to 1/8". This, in a way produces an airfoil with a 2-3" long high point. Interestingly the only planes I have now or remember from my "Active" days in the 70/80's that had any plane induced hunting ( I am capable of doing it without the help of the plane) had thick rounded stab LE's. Maybe Ted/Brett/Paul were on to something - or not - this is Bear country and the Bear has a thick rounded LE on a flat stab, they don't hunt, but, the folks flying them are pretty good and maybe in the hands of one of us with less than Walker Cup reflexes, they might be all over the place.
Airfoiled is the better way to go in general. David wrote an article in SN called "De-Tails" that I had some input to. The alignment issue seems to be less critical than we once thought, because we appear to have discovered that there is a significant tolerance in the alignment, and there's much more tolerance with an airfoiled stabilizer.
The issue with the LE radius is, I think, roundly misunderstood. I think the LE radius itself is probably irrelevant, but, to get a small LE radius with an otherwise 1/2" flat stab, you have to reshape the front of the stab to also create an extended curvature, which moves the likely separation point further aft. The problem with the flat stab is, I think, the separation right near the leading edge, as the radius ends and the flat part begins. All the flat stab experiments ended up with turbulators in the right places to trip the flow, usually one right at the LE, and one top and one bottom, right at the end of the radius and beginning of the flat. I have gone back to airfoiled stabilizers, with a very long "arc" airfoil all the way back to the elevator hinge line, and have never had any improvement from VGs, tripper strips, zigzag strips, etc, probably because my flow stays attached anyway without them, at least to near the hinge line. My LE radius is about 1/16" - 3/32", but that is incidental to the fact that the airfoil keeps getting thicker until about 65% of chord.
Plenty of people have done OK with flat stabs, but I think the alignment is super-critical, and also, it is prone to uncertainty around neutral, as tiny changes in the AoA causes it to separate early on either the top or the bottom, from variation of the surface normal pressure.
By the way, the tolerance on the alignment seems to be in the direction of "positive" incidence, that is, the LE higher than the TE, with an otherwise normal layout. Not that I would ever use a large angle like 2 degrees, but when aligning it, for sure, err on the side of the LE too high rather than too low. Most of the flat-stab models end up with a large amount of down elevator, like 1/4" on a half-inch stabilizer. Get it right, and not too much, and the inside/outside turn is unaffected, but the tracking in either direction (upright or inverted) can be remarkably improved. Based on experience, I would not build in any incidence on a flat stab airplane, but start with the elevator drooped at neutral flap.
I build in 1/4 degree of positive incidence with my airfoiled stab. That's about 1/64" over the chord of the stabilizer.
Brett