there's a few differences, the TM will shoot further and more accurately without modification, when your magazine is empty it'll stop firing and the recoil effect will become something you can't do without!
The 416 DEVGRU is the most expensive recoil gun available, is it £165 better than a VFC? That depends entirely on how much £165 is to you, but it's undoubtedly a better gun.
As dex has said, the recoil shock specific magazines are a little more expensive ~£18 each but you can if you want buy a small plastic adapter that'll allow you to use normal AEG mags, albeit with the loss of the bolt stop when the magazine is empty.
Oh, and don't get it from airsoft world, even though they're claiming that they've knocked the price down it's still a rip! http://www.fire-support.co.uk/product/marui-416-devgru-aeg-airsoft-recoil-rifle-ebb
£20 cheaper and if you give them a ring they'll do the battery conversion for you.