"Good for some, not for others" is a great way to express a balanced critique. These cabs will not meet everyone's needs, but they sure meet mine, especially considering their power/weight/portability. Having said, that I also agree with the eq comment. I definitely like to eq my 15/6. I cut 6db at about 1000hz and boost 120hz-200 about 3db. That's with my J bass with flats and tone control on the bass rolled completely off. I am not a fan of in your face high mids and I find these settings work very nicely for a fat, yet punchy tone with little in way of treble or high-mids.
This is a GREAT post, and points to a key issue here. Unless a player describes his input signal and tone goals, all this talk is meaningless. With a J Bass with flats and the passive tone engaged, the ENTIRE issue with the particular mid driver and crossover in the fEARful spec goes away... completely... zero issue. In that case, you are basically using a VERY good one way 115 cab, for all practical purposes, dialing in the low mid bump that naturally occurs in many bass cabs, and getting the advantage of the amazing mechanical capability of that LF driver.
TOTALLY +1.
As many who have heard my 5 years of too many clips, my tone is probably as different from that as you can get, and all the information coming out of my input signal above 1K totally lays bare any anomolies in the top end of a cab. That is one of the reasons the sophistication of the crossover and top end voicing in the Thunderchild, and also in some of the Bergantino cabs make them totally 'plug and play' for me, which is wonderful, since it allows me to use a very simple, mico head sort of solution with moderate power and standard EQ to keep that basic sound the same across rooms.
The other cool thing for me about the Thunderchild cabs is that when I do want to go a bit more old school, the crossover has a 'gentle upper treble rolloff' filter that really emulates a good one way cab, with that bit wider upper mid dispersion pattern that some feel is key to a good bass tone. Of course, if you want 'icepick' upper mids or super brightness, the Thunderchild is not going to do that (even with lots of boost in those areas), or, as Chef posted, similar to the fEARful also, if you want a more traditional 'top of the cone' break-up response, the Thunderchild nor the fEARful is going to do that. Interestingly, for that vibe, Roger Baer's ML112 with the Faital mid driver and a relatively sophisticated crossover(sophisticated meaning there is quite a bit of EQ applied above the crossover point to even out the response of the top end driver) gives you, IMO, a 'true' one way cab sound with the various benefits of a mid driver.
Lots of ways to skin the cat here! All good stuff, each of which has its own positives and negatives.