I couldn't tell if agexpert was telling you to sell the Bridi or not. http://www.bridiairplanes.com/hangar/dirtybirdy60.html

IMO the Bridi is definitely NOT a second plane by any means but I would NOT sell it either. It is a fine plane, you just need to prepare for it with a low wing trainer first. As a second (or third since you have the PT) I'd suggest something like a Sig 4-star or Goldberg Tiger 2 in either 40 or 60 size. I feel either would give you a good feeling of low wing characteristics as well as a faster and more responsive plane.

You could try to trade/sell one of your high wing trainers toward the purchase of a low wing trainer. Get into the low wing now and you can be in the Birdi next summer if all goes well and depending on how your skills develope. Always seek help when making a major jump in performance levels.