400+ points is very strong opposition, but I'm not sure how much you can safely assume that their winning techniques will be readily absorbed. More likely you'll find yourself in tough or frustrating positions without knowning how it happened. The finishing blow will be a tactic you yourself see coming, but can't avoid it anyway.
The plus side of playing very strong opposition is it's good motivation to keep you honest with your moves. Anytime you play a move you think is not best or play a move that you haven't carefully considered, you're cheating yourself of a means to improve. So being forced to never play for traps, and always expect the best move as a response is certainly a good thing.
So for my 2 cents I'd say go for it, but don't make it an exclusive training technique for month after month. Maybe just 2-4 weeks, and then go back to your rating+200 opponents. As I said the point being the most beneficial thing you'll learn is a certain work ethic behind each move because I don't think their specific techniques will be noticeable due to the gap in understanding.
And of course this may or may not work well psychologically. If you're too frustrated then you wont improve much so keep it flexible and be willing to play someone your own level now and then too.
So I've been having this somewhat insane idea lately about after reaching the 1400 barrier weather or not I should only play CM-FM opposition. Inspired by this blog http://blog.chess.com/demetrios18/my-games-against-gms I got my resaons from this point of thinking. When you reach Class C to most if not all your considered a average player so it's pretty hard to most to get out of this bracet since everything you might know so does your opposition so you will need a little more flair to get out of this bracket and what better way than playing players who have all that and more and no not Class B or A but the big dogs themselves (You can't be the best unless you beat the best right. My second reason is I'm always hearing people say play stronger opponents and when your winning most of your games (doing above average) why not the masters and I'm not pushin it by playing SM IM and GM's anyway like my inspiration did. My 3rd reason is when your at a 1400 rating and playing average chess and it takes above average to get to the next level why not play the best so I can use what they used to beat me up to beat up the people I play in OTB. Please Suggestions by anyone I mean anyone is appreciated. Thank you to those who answered.