For a true tablet, I've liked the Surface Pros I've worked with. (Don't confuse this with the Surface RT or Surface 2, which won't do what you want.) Personally, I like convertible tablets better, in which case the ThinkPad X-series tablets (current version is the X230t) are a good choice. There are undoubtedly cheaper Windows 8 tablets, but I haven't used one; these are the ones that I've had experience with and consider reliable.
Note that neither of these are cheap. Most tablets run a stripped-down OS with an energy-efficient ARM processor; the tablets I mentioned above are a full version of Windows 8 with Core i5s. They're bigger, heavier, hotter, and more expensive than an iPad (or Surface RT etc). The Surface Pro (original or Surface Pro 2) is about the size and weight of two iPads stacked on top of each other, and the x230t is two stacks of two. If you cringe at the idea of paying $1000 for a tablet and then getting it broken two weeks later while sparring, this plan isn't a good one for you.
Personally, I wouldn't bother even if I had the money. Changing colors almost on the fly would be pretty sweet, but for the kind of price premium involved, I think I'd just buy a new iPad and a second saber--one with RGB if you really want on-the-fly color changes.
yeah I've scrapped the tablet idea I've got a netbook somewhere so i'll just install the launcher and use that instead
