From an R/C manufacturers standpoint the 54 and 55 are going to use pretty much the same wing and stab layout. The main difference between the two in that the 54 has more fuse side area. In theory this will aid in knife edge flight. I have not seen any of the 55's struggle flying knife edge though. I think you should go with whichever you like the looks of better as both designs are capable.


Now the tougher debate, 3D VS Pattern type flying. An airplane can be set up to do both but will usually do the 3D stuff better. Reason is that you have to use large control throws and somewhat an aft CGposition for 3D. The throws can be dialed down with dual rates but you loose alot of resolution and precision aerobatics becomes alot more work. Back in the day when I would go watch the TOC in Vegas, I saw many of the pro's fly their precision rounds and then when it was time for freestyle they would change out 1" servo arms to 1.5" servo arms and either remove ballast from the nose or add it to the tail. Sebo used to bolt his prop drilling jig to the firewall of his Katana for ballast. Said he forgot it too many times and this was a good way of making sure it made the trip LOL. The two airplanes you are looking at will do either well, it just gets down to correctly setting them up.