I own a Blitz and I loved it when it was working. (I just need to take some time with it.) I think they are one of the best value markers Azodin has to offer. I don't think $70 is worth the few added features that the Zenith has.
On the other hand, the Zenith X2 looks very promising. 2 piece barrel (which the Zenith has now), CLAMPING feedneck, On/Off ASA, they already fixed the regulator issue, and hopefully the board will be user adjustable.