For the 630,6200,6300 and related AIOs (580,5200,5300): I'd argue LCPDS vs. CommSlot 1 doesn't really matter because there's not much widely available for the LCPDS slot that makes sense or even works at all in a 630+.
After Ethernet, the next most common things are IIe cards and 68882 FPUs, neither of which work in a 630, After that, there are a variety of Interesting(TM) things, but they're very uncommon and some of them weren't available within the US at all. (For example: the picpom tuner/vidcap accessories.) There's also the PAS16 sound card, which, again, interesting if you can find one and graphics cards, which again if you can find one and also they're largely unimpressive video cards by the standards of, say, the LC475's onboard video, which can do 1152x870@256, or the Quadra 700/900 onboard video, which can do 1152x870@Millions and have NuBus slots for graphics cards that can do more, if you need that kind of thing.
Or: If you're so lucky as to find something more interesting for an LCPDS slot, knock yourself out. It would be a great option for a 575 (which can run the IIe card IIRC). But for almost anything else, if you need that particular functionality (better audio, dual displays, etc) then there are machines that are outright better options.
$25 for a CS1 Ethernet card is as good a deal as any, but if they're that uncommon, I'm kind of tempted to say to leave them to the 575 people who want to use IIe cards. (Presuming I'm not mis-remembering that that even works - if not, then that's not worth it either.)
And, if you need both serial pots on a 630/580+ you can always just pull the modem card. Having something filling every hole isn't really a requirement.
