Sorry, quick detour to the Boss RC-2. I bought one for similar reasons, although I wanted one to sample noise loops. The RC-2 is great, and incredibly compact, but the deal-breaker for me was that there was no way to do a one-touch fade-out of the loop (i.e., ending the loop and have the volume automatically taper out). I found that was something the task required, so I sold the RC-2. The RC-20XL, however, has that highly useful fade-out feature, and although the unit is bigger, it still isn't that expensive for such a live-friendly solution. Gassing it big time.
Another live-friendly (but considerably more bulky) option is the Roland PK-5/PK-5a pedals and a sample module. They have a 'sound effects' pre-set that offer exactly the kind of control options that you're after (but of course, it makes no sound on its own - you'll still need an appropriately configured module - but it makes the job much more satisfying and gives loads of cool options besides).