jmn69,
First off, I think the comparisons aren't exactly perfect with a 5 inch all steel gun VS a alloy framed 4.4 inch gun. If it were a 4563 compared to a 220 it would make for a better match.
I don't own a 4506, but I do own its little brother the 4566 and it is fantastic.
Either would be great for fun or home defense. The 220 is a great gun and will last a lifetime. I think the 4506 is a great gun, and will probably last two lifetimes. Being all stainless is a big plus to me. Not to mention if you wanted to bump up the power level to 45 super, I believe all you need is a spring upgrade on the 4506.
I know the following is not a 4506/220 comparison, but it is a side by side comparison of comparable SIG/S&W double stack stainless nines. Which oddly, comes close to the same results I had with a 225/3913 comparison.
SIG vs S&W Head to HeadI have a fidiciary duty
to inform you, like BobCole has done, that on the resale market you will probably get more for the 220 than the 4506.
Either one you get will do the job done for you, let us know how it turns out.
chissel