JFD
I've been shooting my Para P16 for a couple of years now, thousends of rounds each year. So far I replaced the sights with a Bo-Mar rear, my own front, put in a two-piece full length steel guid rod, replaced the recoil spring with a (I think) 18 or 20 lb, red shok buff and.....no, thats it....
Accuracy with good bullets is good (±30mm at 25m - off hand). I don't see a use for a magwell with that big hole and sharply tapered mags - for now at least. Meggar mags (I think from Italy) are real cheap (±USD 40 over here) compared to Para mags (±USD 160 over here). They hold only 15 x .40Short&Weak but work good as stripper/emergancy mags. I've got 3 Para mags, two with the Rescomp shoe (for 18 rounds IPSC box compatible), the other the normal 16 rounds (17 if no-one is watching.... ).