Compass B505, Compass B510 or Britax Parkway Booster?

My tall and skinny-minnie 3 year old will soon outgrow her (awful - don't buy it) Evenflo Triumph 5. She's 2 inches from outgrowing it, and it is sooooooo uncomfortable...the padding coosh is all but gone. I'm looking for a as low as 36"/30 pound booster as I don't want to just get her another carseat, and want to transition her into a booster when this seat finally dies, within a few months, I'm sure. I know, I know, it's best to keep kids in a 5-pnt as long as possible, but she's about to grow out of it!!! (which would be even MORE unsafe).

Anyone have experience with these boosters? I've read great reviews of the Compass B505, can't find anything about the B510 (new I think) and the Parkway.

Thanks for your help.

The Compass Seat is a better product. The upper portion of the seat raises to keep the childs shoulders along with his head within the seat. With the Parkway seat, only the head support moves upward. The B505 is also wider and it folds for storage.
The B510 is a newer model. It has deeper wings for addtional side impact protection.