I agree on all counts. RS has always been a one-man operation, and it ebbs and flows with his real job. I skimmed through the version history, and there have been only a few enhancements over the last few years that add to the user experience. Most are minor bug fixes, code changes, and new license schemes. Pretty boring stuff.
The continued inattention to the transonic and supersonic drag models is baffling. My rocket projects have also grown to be faster and higher, and I can't accept that inaccuracy in the simulation. My order of operations is now Thrustcurve (quick and dirty), OR, RA, and RS a distant fourth.
RSPro gives you 6DOF, splashdown, and customizable drag profiles. That is all that is above and beyond regular RS, from what I can tell. I would value that at $250, not $1000. If you really need extreme splash patterns, you are probably already using something other than hobby software.
I was never a big fan of Open Source, but now I think differently as it is making a big impact in my day job. OR started off as a blatant knock-off of RS in my view, but it is now becoming the standard with a cadre of programmers behind it to keep it moving. Any company that sells expensive, proprietary, and especially stagnant software will not last.