Are internal component upgrades worth it.

I thought crites was closed...they dont have a kit for Cornwall IVs i believe tho. Is Volti another seller?

I think addressing the cabinet concerns with adding internal bracing and something like Norez would yield much greater results than messing with the crossovers.  If I was a novice, that's something that I'd look at first.  

If that's a bit beyond what you're comfortable with, you could find a local cabinet maker or wood worker than can do it for you.

Any modification you try should be something reversible in case you don't like the results.  Any change in the sound could b for better or worse and there is rarely anything that would constitute a universal upgrade.  While often praised, I know folks who don't like the Crites crossover upgrades, for example.  Making a box more rigid does not necessarily improve the sound (not all box resonances are "bad"), and even if bracing the box is a positive, you will probably want to make some other adjustment, such as changing the amount of internal damping material.  It is really a matter of tuning, which means trying different adjustments.  Note too that adding bracing decreases the internal volume of the cabinet and that changes the tuning.  As to upgraded parts, the biggest difference will be the choice of capacitors in the crossover, and again, you will have to listen to the results and be prepared to reverse the change if it is not an improvement.

Another completely different avenue for improvement would be to consider a different amplifier.  The Cornwalls are good candidates for being driven by low-powered tube amps.  The sound of such amps might be something you will like, so you should at least try some low powered tube amps with your speakers if you can.  In most set ups, 40-50 watts would be plenty, and some listeners might even like 5 watt amps with your speakers.

Ok, ill have to think about that...All good advice for sure.

I believe Volti learned most of what he knows from working with Klipsch speakers and has surpassed them, and seems really grateful for this path.