I currently have an m17x r3 (with an hd6990m) and a dell xps 12
(if you know what the alienware 13 is skip to my questions)
I have seen the alieware 13 which is almost ultrabook sized with a capable 860m but you can also connect an external desktop gpu (which you have to spend £200 on adapter and then buy the card)
It sound really cool and means you have a capable small laptop for gaming whilst away from home (lunch time at work for me mainly) but also when you get home you can use a very powerful gpu to max out your games.
1) Is the cpu of the alienware 13 going to limit many games and will it be that noticable? (passmark 3422 - dual core) my alienware has quad core passmark ~6000 and my xps12 has a i7 4510u with passmark ~4000
2) Is it worth the upgrade cost I will be losing some hardware benifits e.g. less ram, only one hdd, worse cpu than both my current laptops, no bluray drive but I will have one device that will be much better for gaming on the move and at least the gpu will be much better when at home. I'm guessing I can sell my laptops for at least £1000 combined (I've not really looked into it) and at the moment with the 12% discount I can get the alienware 13 with the 1080p screen and the gpu adapter for about £1000 (will need to buy a desktop gpu as well) will also need to buy an ssd as it comes with a hdd at that price but their ssd upgrades seem to be more than buying one seperately (so can have a spare external hdd)