Make no mistake, I want 1/2A boosters. 1/4 could be fun, too. I read about someone flying a Farside using 1/4A boosters in the first two stages, on a baseball diamond. Sounds like fun, but I'm afraid of the risk - will there be enough buyers to justify 1/4A boosters?
So, here's my take on how to mitigate the risk on this part of of the motor spectrum. Build only T motors (13x45mm). Ship each pack with one 18x70mm empty casing to be used as an adaptor. Pre-print a dashed line on the casing where the user saws it down to 45mm for use as a shorty case. One motor could be used as 13x45, 18x45 or 18x70mm. If users have a hard time making one case last for the entire pack (ie, 3 or 4 motors), then ship one empty case for each motor in the pack.
If a smaller (than T) size is deemed necessary, pre-print a cut line on it. I know 1/4A3-3T and 1/2A3-0T motors can be cut down to 1.25". I've done if before (in what else, a tiny Midget
The key here is that, for example, one motor takes the place of three. An A10-0T can also be used as an A10-0S and an A10-0 (~A8-0).
In the case of this particular motor, I'd like to see the thrust tail shortened a bit (in time). It's my understanding the better description of the motor is a 1/2A with extra powder loaded on it to keep it from bursting during the initial thrust spike. That may or may not be true, but the point is that, while a nice spike is good, the low tail is undesirable.
What all this leaves out is 13mm B motors. Perhaps those would use a longer case. I suspect there may be some serious technical challenges with these. MPC had problems. And I think Centuri did, too. And that may explain why Estes never did B-T's.
Now, if a reliable B motor can be built in a 13mm case, then the same adaptor scheme described above may apply. I have a hunch there's a certain minimum aspect ratio (diameter to length) that applies for getting high reliability. IOW, you can't put a big core in a narrow motor. So a 13mm B14 might not be possible, but I'm not an expert.
Anyway, that's my two cents on the 1/4A, 1/2A and A impulse segment of the spectrum.
Regards,
Doug