Will moving to a hydro assist make for better street driving? Meaning less clunky steering, tighter steering, less vibration transmitted through when hitting bumps/potholes?

 

If you're getting those issues now you need to see what is causing those issues. A Hydraulic assist steering will not fix that problem. Clunky steering would be worn/loose components and/or bushings. Loose/flighty feeling steering can be the same, along with an improper alignment settings(toe in/out, caster). Vibration/steering input from what I've dealt with is from the angles on the drag link and track bar being different, along with again, improper alignment and/or worn/loose suspension/steering components. A hydraulic assist would be a very expensive way to attemp to band aid or cover up those issues.

My Teraflex 3" longarm rides and steers better than stock, and has never had any of the issues above.

I would check all your front end steering/suspension parts for looseness. And check what your front axle caster is set to. On my JK anything under about +4.5 deg on my 35" tires causes it to feel loose flighty on the highway. Mine is set to +6.2 deg, since thats as best I could get w/o causing a sever front d/s angle and driveline vibe.