The S2000's steering is actually quite stable at high speed - it's the rear end that fidgets and tramlines. One learns to hold the wheel lightly and just ignore it. At speeds where the S2000 feels like all hell is about to occur, the NSX is just GT-cruising.
The NSX runs a lot more caster, so I cannot see stability being an issue. Rear kinematics are a lot calmer, too.
The S2K's rather bereft of feel (even with chassis braces) compared to the old stager. I personally don't mind the twirly steering - it suits the GT car nature. The S2000 is more mad.
So I'd be inclined to compromise with an Accord rack if you're so minded.
Of course, the Evora uses an old Accord rack - a proper hydraulic one. You'd have to install an engine pump somehow, so it might be a bit harder. But I preferred the way the NSX drives over an early Evora anyway. Found the steering a bit slow/heavy to unwind when the tail steps out.
My car with the loveliest steering is actually the Leg End! Hydraulic, just like the even lovelier steering on my old Prelude. Something got lost on the way...
Nick
“I find myself irresistibly attracted to cars that nobody else buys. The NSX is a classic of the genre because nobody buys it and yet it’s a fantastic car. It’s got a wonderful compactness and simplicity and unpretentiousness to it. Honda rudely continues to make them whether we like it or not, even though there can be no commercial logic in doing so — I thoroughly admire that.” Rowan Atkinson