Rest assured that any sampler you buy today- be it a Yamaha, Emu, Akai or whatever do NOT sound bad!!!!! They all sound awesome and have very deep synthesis/DSP functions, heaps of polyphony and heaps of (overpriced!) options.
After thinking about your questiion above, I've come to the conclusion that you might be better off with a Yamaha for the simple reason that it comes standard with most features that are options on the Emu.
No I'm not bagging the Emu (I'd love to own a fully expanded one very dearly!). It's just that short of getting an E4XT Ultra (with nearly all optioned fitted) you will need to expand certain features (most notably RAM, outputs and effects)) to get more practical use out of the sampler.
It all depends on how much money you have to spend. The Yamaha A series can be fitted with a board for extra outputs and digital I/O and extra Ram (of course!), the fantastic effects come as standard.
Have you checked out Akai's S5000/S6000???? Here in Australia, there has been a massive price drop on the S6000!! I saw one in a shop for $6,995 (It did cost $9,995!!!!). And this has practically all options fitted with 128 notes of polyphony to boot! Initially it's software was a bit buggy but Akai seem to have been onto the problems. I'd seriously check one of these machines out also. They are a massive step up from the older S series machines.