I've been building cabinets and buying mid-grade and high-grade Birch by the truck load for many years. One thing is the TM's are NOT a true Russian, Baltic, or any other form of high-grade birch, where EVERY one of the 13 layers is actual Birch. The so-called 'Birch plywood' used on the TM's is similar to the Home Depot grade birch plywood where the outer layers are a Birch veneer, but the inner plys are actually Poplar. It's technically sold as 'Birch plywood' because cabinet (not speaker cabinet) builders don't care about the inner plys, they only need the face to look nice.
Don't get me wrong, this does NOT mean the TM's are inferior - Just the opposite in my opinion. Actual Russian or Baltic birch will have a more dead sound. Most of the time way too dead like concrete blocks with speakers. You could make the argument that the better birch is stronger, but I've never seen any rip or separation tests to prove anything.
It is my opinion that Egnater has hit a great happy medium with resonance, tone, durability, and portability with the TM cabinets. As I said in another recent forum, my next purchase will be a pair of TM 212's, or a pair of Vox 212's, both which are incredible cabinets for the money.