Thanks to all for your replies. Being on a fixed income now, I've looked at the relative costs of reloading for practice rounds, and of purchasing commercial ammo. My consideration of a 9mm now has to do with the availability of commercially loaded ammo at around $24/100. I can put together .45 or .357 rounds for about $16.00/100 at current component prices using cast bullets, and so the economies of reloading in these crazy times are (at least for now) diminishing.
I still will reload, simply because I enjoy it, but to have an alternative supply of practice rounds available commercially at reasonable prices is also becoming increasingly important to me.
I have read of many good experiences with the Sigmas, and the current prices of them are a really strong draw. The dimensions and weight of a Sigma, while larger than some semi-autos on the market, are still much less than my 625 4" revolver, and might be a good step-up from my 642 or SP-101 as a carry option.
As soon as I recover enough from my shoulder surgery (done last Friday), I'll take a closer look at a Sigma.
Thanks again.