Vne scares me more because it was determined in a nice new aeroplane. A bit of slop in the hinges and if the flutter starts your aeroplane could destroy itself in seconds. One can manage G to some extent.
Personally I'd never spin a C152 which is 40 years old. I'd rather be in a CAP10 with a aero's FI sat beside me.
Hmmm, both these comments have a their core, a reference to a concern about airworthiness based upon age, or by inference, time in service.
For general aiviation airframes, with few execptions, airworthiness is based upon condition, evaluated against a standard established by the original manufacturer, relative to a "new" aircraft.
It's sorta like: "dimension x for intstallation of a new part, must be between a and b, in service, that dimension may be as much as c, and the aircraft is still airworthy" If it is tighter than "a", it is not airworthy (though some installation rework might be possible), if it is more loose than "b", don't install it. If, during inspection, you find it between "b" and "c", it's okay to leave it in service - IT IS AIRWORTHY, if it is beyond "c", replacement is required.
If, at the time of development of the original instructions for continued airworthiness, something important was missed, and problems in service began to pop up, there are many tools (Serivce Bulletins through to AD's) to catch this. That is a reason I like 40 year old planes (mines only 36), they have the in service experience to figure out where the problems are!
If it is your preference to not spin a 40 year old plane, I suggest that you not fly it at all, because to think that a spin (presuming it is spin approved) causes stress on the structure, or risk of flutter, which otherwise would not be encountered, is head in the sand thinking.
If you are willing to pay the price, and/or make other operational compromises, to assure that you are always flying "new" planes, that's perfectly fine. Other pilots choose either by preference, economy, or operational need, to fly older airplanes. As long as those aircraft are maintained airworthy, there is no reason to consider them any less safe or capable than "new" ones, when operated safely within their limitations.
As for powerplant, Vne is not power dependent. None of the times I have flown to speeds exceeding Vne (Vd) have required full power. I always use some, just to be kind to the engine cooling. Vne is based upon and limited by indicated airspeed in light aircraft. I have flown aircraft which are capable of exceeding Vne in level flight with high power settings. You just don't do that! (oher than for testing purposes).
As Vne is limited by indicated airspeed for light GA types, as long as the airspeed indicator is not past the red line, you are not going too fast in that plane, regarless of altitude or the engine installed. When Mach begins to be a factor, the airspeed indicators are equipped with moving "barberpole" redlines (with which I have limited experience).