Yes, they are squattier than most designs. That is intentional and is because of the particular parameters of the 40-1297 driver. Greg Monfort who posts as GM on the single driver forum came up with the plan. He is very knowledgable when it comes to ML_TL's, TQWP's, rearloaded horns, etc. Much like Wayne is here with the high power, low distortion 2-way and 3-way high efficiency and horn systems. It's a great time we live in to be able to exchange information and ideas so efficiently.
I've played with the supertweeters a bit with my 8" fullrangers, but not with the pipes yet. I'm afraid I could mess up a good thing. I might have to do some trial runs. I have two different RS piezos to experiment with. Thanks! Jerrod