Same advice - you wont go wrong in the main, and the ones supplied by JD have a warranty as he gets them through official channels so your covered. The CTW has come on a long way since the launch of the MX-1 and the X-Max which were pretty Poo, but the new MX-2 are pretty damn good!!
The big thing to remember is its not a Systema PTW - it is damn close, but its not quite the same (97% but not 100%), but then again they are not £1450 either so its very good weapons platform for less than half the cost!!!
Even Systema PTW's go wrong - I purchased a CTW and my mate bought a PTW as he is a sad arse with no girlfriend or life and so had more cash: he poo poo'd my CTW as he said it was 'Shite', sent it to Tackleberry for the £400 tune up and first time out - buggered!!!! I laughed so much some wee came out
As previously mentioned, get a good battery ( x 2 if possible), definately LiPo and a 20C discharge rate as a minimum. Spare mags X 6 and an M110 spring. With a CTW its not about super power - due to the 6.00mm barrel they will out perform any AEG but the bigger the spring you put in it the more strain on the gearbox, piston etc and it will of course flatten your battery quicker.
The key to PTW and CTW ownership is that your moving away from the 'spray and pray' method of combat to the 'controlled, aimed shots' division and its bloody fantastic!!!!!
Welcome to the Clan - STAND FAST....... FIGHT HARD