WE MP5K 'Apache'

Hi guys

I'm very interested in this gun, but you guessed it I've got some questions.

I'm also looking at the CYMA MP5K (good bit cheaper), which is electric. When it comes to firing on full auto, which system works best, gas or electric? Also, for WE's MP5K, I've been told that it's 280fps, 300fps and 350fps. Does anyone know what's going on there? Ultimately which one would you recommend?

Many thanks