WE M4 Katarna or 999 RAS AEG

[dazzer106]

Hi all
As title says I've seen both of these for under £200, the M4 comes with the blue cylinder, the 999 RAS is a G36K with full metal front end, I can't seem to find a real review on interweb for either, so has anyone have, had or used either of these and give a thumbs up or down on them, as I'm a bit undecided in which to get I like the idea of quick cylinder change but have too many M4 types, but also like the G36 with the rail