Bigger, for sure!!
Now let's think why. the main thing with this is from the fact that putting a horn in front of the speaker, the general sensitivity in the pass band will be increased, and also the efficiency.
Grey Bass Reflex 522 L, Black SKHorn 522 L, SPL at 145 V, same tuning frequency
The main issue appears when using more than one and using a specific type of music material. Techno music is most of the time centered around 45-80 hz .there is right where this sub has its impedance minimum. If it is to be chosen between this SKHorn and 2 dual 21DS115-8 in very small enclosures, like 310 litters net each, with similarly big ports as the SKHorn, those would be better equipped to withstand a whole night of using them to their limit. Why? because of the content type.
Most of the energy being centered in that band, the RMS limiters for an SKHorn would engage to keep the average thermal power into the sub at under 2-2.2 Kw (which IMO is very risky, given the fact that the excursion is lower exactly where the power input is higher so the cooling is poorer) so even though the peak SPL capability of this sub would be within 2 dB of that couple, in use, those 2 would be much louder than this one because the RMS limiters would not engage if set to the same threshold. also the power compression would be higher on the SKHorn, and extremely low on the 2 dual BR because most of the time the drivers in the BR would see under 1 KW in the 40-75 HZ range and in that range more power will leave the voice coil firstly because the excursion would be higher, so better cooling and secondly the power conversion efficiency would be higher so more energy would be converted into sound instead of heat.
In Grey is 2 dual 21 BCDS115-8 310 L net BR Efficiency
In Grey is 2 dual BCDS115-8 310 L net BR input power 145V on 2 series Ipal, 160 V 2 drivers paralel, 2 subs parallel
In Grey is 2 dual BCDS115-8 310 L net BR Max SPL 145V on series Ipal, 160V on 2 drivers paralel, 2 subs parallel
So yes, the two would be heavier, a bit larger, more expensive to make, but would require far less power from the wall and will give more long term output than a single SKHorn. So for people who would carry these around from a gig to another, using them mostly on EDM and Techno, it would be a better solution. it wouldnt sound as clean as the horn, having the driver in front. and also it wouldn't be anything spectacular, but it would be useful for this sort of app which is the most commonly used
So here comes the conclusion. Making it bigger would also make it more efficient. increasing the horn side would gain efficiency higher in frequency, increasing the back chamber and/or increasing the tuning frequency a bit would gain efficiency in the lower parts.
Off course, making a sub tuned exactly for that genre would be even better, like a Danley DBH 218 horn which keeps the efficiency very high but also it keeps the excursion low for a clean sound, but high enough from the high pass crossover to help the drivers cool down.