CHOcobo, I can tell you about those 2. Played with the 4D100 for almost a year( record! ) and with the BM200 for about 4 months. I really liked the BM200 18x20, I just switched to the YT Prestiges because I couldn't find 2 similar ones spec-wise and the grip had some flaws.
In stock form, the BM200 is much more powerful, it's like you crush the ball at every single swing you take. Very solid from all areas of the court, groundies, colleys, overheads, serves. Just take a swing and watch the bomb fly over the net.
The 4D100, on the other hand, is much more precise, a scalpel, as many here like to refer to. Underpowered( remember, in stock form ), it seems like you can put the ball wherever you want with your own hand. Excellent for old school players that like to rush to the net.
Each one has great qualities, and I'd be playing with the BM200 until now if I hadn't had the issues with the overall quality of current Dunlop frames( a shame, given the fact that Dunlop used to have one of the best QC out there ). Excellent feel, great plow through and very spin friendly, unlike the 18x20 string pattern might suggest.
I used to have a lot of lead tape on my 4D100s, 5g @3&9 at first, then 6g @3&9 and 1g@12. It made the racquet a lot better, without compromising its excellent manuverability.