I've read in a couple places that even with a diaphragm-style (Mallory, Holley etc) return regulator, the factory pump will eventually burn out. Any input on this? I'd rather not have to deal with that sort of thing if it's avoidable.

There's no real rhyme or reason - the pumps run, then they don't - it's a fact of life - usually no warning or signs of it - it just dies. I replaced my pump when I swapped to carb, and I'm using the Mallory reg, and 3 years later no issues. I used a CarQuest pump.

I used a TBI pump when I went carb'd with a Jegs Billet non-return regulator. It can handle up to 20 psi of inlet psi. This pump has been in a few years and it was used when I put it in. No problems and Im also using the same pump to run my nitrous.

My Dad removed the TBI in his 1-ton truck about 15 years ago for a carb. Same pump, capped the return line and uses a returnless regulator (which EVERYONE says you are not supposed to do. Never had a problem. It only leaves the garage when he's towing a trailer, but he's got more than 100K on it since the swap.

I'm sure it's a fluke, so I did my swap with a return regulator just to be safe.

If you are using a return style regulator, it shouldn't affect the life of the pump at all since the pump doesn't see that it's any different than the TBI.