50 master cards is probably a bit too many. The difference in ability with some of the top players of CTB would be far greater than the players of the lower spectrum. Mikhe's ranking system seemed pretty good as not everyone is ranked with the same title since there are some players that are better than others. With more titles (like mikhe's Vpro, Pro etc.) it may encourage players to try aim for a higher title than the one they are currently.
So either less master cards, or different titles. Mikhe's ranking system is a good start and, of course, the titles that are given to plyers should definitely be discussed by a few other players for accuracy.