Smokin and Yooper. It took me a while to convince myself to go with a low stretch string on older limbs. But the older limbs just look very sturdy to me. Their limb tip overlays are at least as thick as those on the newer limbs. Older limbs also carry their width further toward the tips. They're just "beefier."
I've never had any trouble, and the low stretch string improves performance and makes the bow even gentler on release. I think that with a properly padded loop, low-stretch strings are actually easier on the bow because they greatly reduce all of the limb flexing/vibration at the conclusion of the shot. Regardless, I wouldn't feel too bad if I blew up a set of older limbs, though I don't think it's any more likely to happen with a low stretch string than with dacron. They're not really rare. In fact, there are a lot of them around, and, given all the new limbs that Bear is churning out, folks seem less interested in the older limbs so they're also available at very good prices.
By way of illustration, I just picked up a Green Stripe riser with a set of 50# limbs so I again have three sets of 50# limbs. One back-up set is enough so I've been trying to sell or trade the third set. Virtually no interest. My interpretation is that there are a lot of older Bear limbs available, and the market for them is rather weak.