Nice car Jason, I remember seeing it in Moncton now. I'm twisty roads focused so your track pack wheels and brakes caught my eye. I always pay a bit more attention to those cars. Yours was nice and clean.
I have very limited experience with your transmission. All of maybe 600 km's highway driving a friend's car, so no pushing it too much on the 1-2 shift. My car runs the TR-3650 five speed and shifts well across the board.
I'm not a tech, just a gearhead that reads a lot and assimilates a lot of information. I can say that when I drove my friend's 14 GT, my personal feeling was that the shifts on his car were not as crisp as in my car. I've also noticed that within the aftermarket world, BLOWFISH racing has come out with a shifter brace for our cars. It seems to be quite popular with the 5.0 guys, running your transmission. If you're lucky, you're issue may be as simple as a shifter issue. Especially if the dealership tells you they can't find anything wrong...
Quality shifters have also been very popular upgrades recently. Two companies, MGW and BARTON, are each making precision engineered and top quality built shifters. I'm talking firearms industry quality engineering and advanced alloys for rigidity and precision. The old popular shifters such as Hurst, Steeda and Pro 5.0 simply don't match up to these guys' engineering and precision. These are avenues to consider for you. I'm running a Hurst billet shifter and if I were redoing it, it would be BARTON or MGW.
The big American forums have threads on everything. You have to be careful not to take what's on there as gospel, but if you Google your specific issue, I'm sure something will come up. It may give you insight on where to start.
The big American vendor sights may also have ideas if you talk to some of their tech guys. I'm talking about Late Model Restoration (LMR), AM (American Muscle), CJ Pony Parts and Brenspeed.
And of course, the speed shops you have been enquiring about all work on cars that regularly race most summer weekends so they would be a very good starting point. Either Pete in NH, Ted Lewchuck in Montreal (Mustang Direct) or Joe Dasilva in Pickering would be good sources of information. These guys get everything come through their shops and all three are racers themselves so they've all seen a lot.
A call to any of them could be your start of a relationship with a speed shop. It does not matter which one you pick, just know that they are all very busy and their time is very valuable. If you do call one of them, maybe have thoughts in the back of your mind to eventually go and give that shop some work. Many people want to tap into their knowledge but not all are willing to give them the work. For them, their time is much better utilized speaking to patrons in their shop than someone on the phone they may never see.
I hope others with more wrenching experience chime in for you, especially if they have experience with your setup.