If the universal-fit sensors require soldering, I'll gladly spend the extra money on a sensor with the proper connector. I've already heard plenty of Bosch horror stories.
Last time I had a scan tool hooked up, the O2 sensors appeared to be working; the rear graph looked mostly like a scaled-down version of the front one, which suggests to my untrained eye that the cat is still working, at least at idle. But this was before P0420 codes started popping up.
Naturally, this is definitely something to be handled after battery cables. Just brainstorming out loud, that'* all.
2007 Pontiac G5
1999 Pontiac Grand Prix GT - Stock engine ate transmission.
1997 Pontiac Bonneville SE - Cammed engine ate transmission.