Down-firing essentially alters the room's effect on the sound from the subwoofer(s). There are some reasonably-priced down-firing subs but any time comparisons are made, the methods need to be consistent.
Which small builders have the financial resources to really do the testing & measurement in the way the large speaker manufacturers can? Unless they're able to rent time in those facilities, I would argue that none are able. If you check driver frequency response, they usually indicate that below a certain point, it's not actual measurement and that's because it's terribly expensive to create an anechoic chamber that's able to meet that definition at the lowest frequencies. The cost of the testing facilities has to be reflected in the price of the speakers and subs. The cost of Dynaudio's anechoic chamber was substantial.
View attachment 76947