hmmm I use mine with my MPC-1000, this works fine, but the XT is hooked up mostly as a controller for software (BFD2 Kontakt)
if you're going to use it standalone I'd grab a large, capable sampler.
I've tried the laptop (MBP) route before, but if you're going there, also get a (very good) midi interface, and converters, since the stock i/o is unsuitable for serious production.
The advantage of updating it, contrary to disconinuation? That's for me exactly the ARGUMENT NOT TO GET A LAPTOP! Please let me explain: The turnover in production cycles (laptop models produced) is very high. After 4 years no one supports your laptop anymore. When you get it, grab all the software you need, since updating it 4 years along the road is NOT AN OPTION - you cannot expect the software 4 years from now to be compatible with present laptops.
Also a professional rack sampler (when cared for) will last a decade or more, laptops? Not so much. Built for consumers. (2-4 year lifespan) So?? For software and upgrades, IMO the hardware sampler and laptop are equal. Ease of use? It depends... a big screen is nice to edit on, laptop wins. But on stage or in a rack the sampler is a hell of a lot more usable than a finnicky laptop, with PSU, midi converters etc. hanging out, ppl. spilling drinks into it, it's vulnerable and the sampler in the rack is not - sampler wins. As for sound? Equal IMHO. Price/functions? Sampler wins: a good quality complete laptop setup will cost 4000$ at the very least (incl. converters, midi, software) but you can use it for production, website, artdesign, administration. So it has it's uses.
My first choice would be an Emu. (E4XT Ultra or simular Synthony Music's Synth & Midi Museum
) Add a BCR2000 for the CC controls and you got yourself a setup. Advantage of the MPC series is of course the built in sequencer. But the Z series Akai mentioned above, would be nice as well. There's a couple of Yamaha I'd also look at.
I'd advise against the iPad. getting midi into it is not timing accurate.
Also, I have an electribe ES-1. It's great, but there's no control over individual samples (envelope, trim etc.)