Juxta Pose:I've been told that big subs are used less for electronic music, as the lag of a big driver can put the beat out of time with the higher freq...Is this true?...Should I be running several small subs( say 4x 12" or 15") or should I head towards a couple of big subs(like two 18")?
What is important is the relative phasing of the subs to your kp-362s in the frequency region where you crossover to the subs. I'd recommend the use of an electronic crossover with steep-slope filters so that the crossover region is minimized.
Some subs have a phase control that allows you to add or subtract delay in order for the subs to be adjusted in the crossover region, but you can also do this with other preamps, electronic crossovers, etc. I see no other issues regarding "being out of time" related to subs.
Having one large sub or a collection of smaller subs is usually the choice of the listener, but there are articles by Floyd Toole mentioning the advantages of multiple subs in small venues. Having multiple subs allows you many options for venue placement. If you are in medium-to-large venues, then larger subs will be required to achieve the kind of SPLs that your audience may demand. How large a venue are you trying to fill up?
Juxta Pose: I've even seen some 21" subs about two! Although they seem pretty impractical transport wise an seem to be a bit of a show piece for most who have them( 15" or 18" subs I've used have given plenty enough bass).
I'd recommend looking at compact subs if you move your rig often, or even maybe not so often. Look especially for tapped horn subs such as those from Danley. Klipsch makes subs (e.g., KPT-882) that are fairly large boxes. All of these devices are fairly heavy, however (~70 Kg or more).
Chris