Hey, Don! I've never heard the N3s, so I can't speak on that one (would love to, though

). Comparing these to the stratas (and keep in mind this is before pretty much any of the components in the SSVs are broke in yet), they share in a slightly darker overall tone to the sound. The SSVs are very articulate mids-highs, but are very "matter of fact" in how they deliver. In comparison, the minis have an airy kind of ambient way of making music, maybe even a little breathy and delicate (which for some kinds of music is kind of a fault).
The SSVs have them hands down in dynamics and an effortlessness in presentation (I got the minis dialed in close regarding effortlessness, but that was in a 15x10x7.5 sealed room). Also, the minis' powered drivers are good, but the servos on the SSV are just a whole different level, and sealed vs. ported, not to mention sheer difference in driver area/sensitivity. . .
Short version - comparisons can be made, but these really are apples and oranges to each other. I very much like the minis, and could probably have easily lived with them in another life (and honestly right now am missing the planar driver sound just a little bit), but part of the desire to change things up was just that - to change things up, and with a slightly different set of goals in mind with what I was after in how the speakers sound.
Thanks Ruben! Unfortunately, I haven't heard the SV in their original form, so I can't make any comparison. However, Danny has heard them as well as having heard this crossover in Guy's original ported cabinets while doing the design, I think - might be close enough to get some thoughts?
Regarding the cabinet size/shape/placement question, I just took out a ruler and yep, you're pretty close (a little shy of 3 feet out from the wall). I did think very early on about doing the coax OB and the bottom sealed. Also, in a very early design of the cabinets (before the decision was made to do the stacked MDF thing), I went off the original sealed servo sub box plans, which would have made the cabinets about a half a foot less deep. In retrospect, although the proportions on these cabinets are very nice, maybe for this room, in this situation, I should have stuck harder to my guns and kept with the smaller/fatter cabinets. . . but that would have meant a wider front baffle and all that entails. . . but I digress; thus is the nature of living on the edge.
One of the details I made a point of in having these cabinets built was doing machine screw inserts for just about everything. A snag came up that ended up with the amps being secured with wood screws, but everything else is either bolts or machine screws, specifically to make it easy to take things apart and put them together again for tweaking/tinkering purposes.
I COULD be game to have another set of cabinets/baffles done if SOMEONE were POSSIBLY inclined to take on an experiment. I think I've got enough closet space left to make it work if/when I move the ETs off to a new happy home. . .