For 200mg caffeine, you would need just over 3 x red bull, which isnt enough to make you sick, especially if you dont drink any additional water/sports drinks in that time. The myprotein product is going to be pretty good, and, like you say, contains no liquid, which is easier on your stomach.
Potential problems I can see:
* 200mg straight up might be too much – I prefer to take my caffeine over a longer period (this might not be a problem for you)
* Caffeine in its anhydrous form (which means salt) is generally more potent that in liquid form, so is equivalent to more than 200mg from liquids.
It comes down to individual preferences though – I dont like caffeine in tablet form, I find it gives me cramps. You might be fine though, so its certainly worth a try. Im sponsored by myprotein, and havent had an issues with failed dope tests, so you should be fine.