Yes - very small. I did some testing a while back and about the maximum length is a little over 0.1 seconds. Any longer and you will never be able to get the original pitch back. Have a search on the forum for Pseudo Sampling. I spent a couple of days intensively fiddling around with the Digipro.
The good news is that with pseudo sampling, you can chain together a bunch of short samples using trigless trigs and other tricks. Push your Mono to the limit - it's fun