I have not heard the 25 - yet. However, I have heard the 212/SE. In my opinion, it was hugely better than their older downward firing subs, which I always thought were real "thud buckets" every time I heard them. Not so here.
I never really trust speakers with drive units that don't directly face you or fire at least directly at you at the listening position in some way, shape or form.
The 212/SE is seriously dynamic. Hugely impressive over a short period of time. The real question I would have with it is "can you cope with it?".
In the small system I heard the Pursuit in, pictured below, the system was running in two channel hi-fi mode. This all metal driver system, like other cone metal based driver systems I have heard in the past, can exert serious control over the air in a room.
The fact that I heard this in 2015 and still remember it well shows it was impressive. Very good value for money if you like high SPLs and want to move serious air with copious amounts of bass. OK it doesn't look very high end, and I guess it wasn't, but I heard better dynamics in there than the very vast majority of systems can manage.
A stack of 6 25s I predict will be awesome, but ONLY if your in the mood for the impending assault. Otherwise, switch them off!!!
The small room means that in larger ones you'd need to scale up the subs to get a similar effect. So a huge brace of 25s could well be in ticket in your room Ron, paired with the Gryphons.
EDIT: just discovered the 25 uses carbon fibre drive units. As a result I don't think it'll sound quite the same. Wasted post, maybe... but if the Pendragon towers use carbon fibre units the 25 might be a great match. I'm a big fan of using the same driver material over as much of the FR as possible.