Every MBP owner I know has had their SuperDrive fail on them already, so I'm not sure removing it would make a lot of difference to functionality! Both of mine failed too; the three year AppleCare runs out on my second MBP at the end of next month, so I'm debating getting it fixed while I can. (It means being without my main laptop for a week while they fix it, as well as two hours travel to get to the Apple Store; probably not really worth it.)
The external drive I bought when the first MBP drive died hasn't been used for more than a year anyway; I did rip an audio CD on my Mac Mini last month, and tried to burn a CD-R on it, but failed (ended up burning it on the PC instead, which worked fine).
My guess would be for "HDD/SSD/optical, pick two", and I certainly wouldn't miss the optical drive: I'd be much happier using the external drive the rare times I need one, and an SSD would be nice for performance if the price is sane. There are already retrofit kits for this as an upgrade