No idea on the nutritional breakdown however I will offer some opinion here.
I would argue that the smaller the catfish the worse the spines are in terms of how they may damage the internal organs of a bass. Anybody here know what a madtom is? Getting stung by one of them in the 1-3" range can knock you off your feet! I get stung about once a month during peak fish sampling season.
Removing a spine wont do much in my opinion. Over evolutionary time, I think bass have evolved various ways to avoid eating foods that are harmful to them on a broad scale not individual assessment of prey items. Especially since they co-evolved with those Madtoms I mentioned. I think the both mechanically and behaviorally, bass are not going to be eating tons of catfish. In addition to this, I have caught tons of bass with fish in their throat, and only 1 of them I confirmed 100% that it was a catfish vs. like 3 that I've seen with trout, 20+ shad and 10+ minnows, carps suckers etc. (However you might liek to know it was a bullhead)
Nutritionally I dont think bass are smart enough to know that one is slightly more nutritious than an other. I think that evolution has played those cards for the bass by shaping them both physically and behaviorally the way they are. If catfish turned out to be the best prey item for them, they would have mouth and eyes directed more towards the bottom of their body. And we would encounter less overlap in habitat use of both catfish and bass.
Hope this helps?
If people concentrated on the important things in life there would be a shortage of fishing poles. ~Doug Larson