I too have owned akai's which are all punch but lack any low end.

Side by side comparison of a sampled 808 kick,

Akai S2000: Sounds like a small fart of air going by, absolutely no bass timbre at all, in other words useless.

E-mu ESi4k: Sounds close it loses only about 10% of the super low end, but you can still use it to creat your symphony of 808 kicks, fun fun fun. And surprisingly musical. Great bass timbre.

All in all a much fuller rounder machine, with oodles of filters, easy to use (Made by Americans thank God), no crazy engrish explanations written by overtly technical Japanese manual writers. Oh yeah and the price, the sampler sounds as good as an S5k or S6k, betters the Yamaha's too.

All in all the best sampler for the buck now a days, small convenient, professional sounding, great great midi response, excellent assignable controllers, more in and out's than any other similary priced sampler too,.

If I could give more than a 5 I would, this is a great piece of gear do your self a favor and get one!

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...speaking of which, my biggest (and really only) complaint at the moment is that you can't just save individual samples ("presets") to disk, you have to store entire banks. i'm also not sure if it's possible to fit more than one bank onto a disk, regardless of size. but i'm still new at this, and i could be wrong about both of those (please let me know if i am!).

to sum it up, i love it so far and wouldn't hesitate to make the purchase again. in fact, i don't think it's possible to get a better sampler for under a grand. the only other sampler i think i'd rather own than an ESI 4000 is an akai s-5000 or 6000 or maybe a kurzweil, but those are all about twice as much as the ESI and way out of my price range...