A lot of the early Sig Mosquitos were not very reliable. Tons of problems and only marginal accuracy. My understanding is that Sig has worked hard to correct those issues and that the newer models are much better. A friend of mine got one about a year or so ago and after 500 rounds of jams and other problems and words with Sig...he sold it and bought a Ruger .22 which has been a good pistol.
While I have seen the CZ's...I haven't fired one and can't comment on the quality of their construction, reliability, etc., but if it is like CZ's other stuff, it is GTG.