The ten round mags will lower the already low resale value of a Sigma. Most gunshops are only going to give in the 100 dollar range, since they'll be selling it at 250 or so.

I figure that I'll have my .40 Sigma for as long as I live. I've had it five years already.

A safety deposit box at the bank ought solve your storage problem. Or get a locking gun box, gun safe, etc. Or learn to carry two guns. Shrug.