I've already searched, however, I can't find any that directly compare the similar 200/300/400 models.
Unfortunately you won't find a review on MFIL 400.
Ok - I 'll give some prespective
- 200 (Standard) is a heavy racquet, very forgiving racquet and easy to find the sweetspot . Due to the heavy swing weight - you will find yourself tiring easily after a hour.
- 200 Plus (2006) I have the standard size (27 inch) , it is a tad lighter and a little bigger head size than the 200 standard. Open string offer easy access to spins, this racquet felt a very different for me because of the lighter swing rate compare to the M fil 200 standard. I found the racquet frame too soft, had a hard time generating power.
300 is the best choice of all three models. This racquet has received rave reviews from players - baseliners to S/V players. offers perfect balance of power and control.
400 - I have not play with this model. In comparison the 400 with 300, the 400 offers a stiffer frame, slightly bigger head (means more power) and longer frame. I would think this racquet is perfect for baseline players.
Question 1 for you is what type of player are you? S/V , Baseliner, Pusher or All court player.
Question 2 - do you or are you comfortable with playing with a stiffer racquet?
I currently play with a 4.5 player who uses the M FIL 300, he loves it. He used to play the 400G (older model). He said he like the control on the MFil 300 better.
Hope this help!