The pops are due to slight issues with the looping. Maize is unable to crossfade while looping, so loops created in it, even at zero points, will create a slight pop unless conditions are perfect. With shorter and more dynamic samples such as in the violins, this is very difficult. We did the best we could with the samples we had.
It definitely isn't the best, but it's easy to work with and what I had at the time. We're releasing a Kontakt version along with Maize for VSCO 2 in the future, and looking for other platforms or possibly a release of some of the raw sample base.