Laptop for Blender animations (GTX870M or 2x GTX860M possibly to be upped in future

Hello,
I am in the ‘final stages’ of purchasing a new laptop. I do tutoring as a hobby and I was planning on doing a series of 30 minute animated tutorials/mini documentary-style films on different topics in maths, chemistry and physics. I have started getting into Blender and I was thinking about doing video animations for my YouTube channel.
As I was planning to get a new laptop anyway, I thought I would make it work with Blender as well as possible. For mobility reasons I am pretty much restricted to laptops as opposed to desktop computers. My budget is around £1,600. I was looking at different custom-built Clevo models. To fit within my budget I can either get a model with a single GTX 870M, i7 910MQ, 16GB RAM or (stretching my budget somewhat) I could potentially get a model with 2x GTX 860M, i7 810MQ, 16GB RAM.
With the latter option I thought I might eventually upgrade the two GTX 860M’s at some stage in the future.
Any help/advice would be really, really appreciated.