My point to the long deplane time is not limited to passenger comfort, although I'd avoid a 753 personally (after my first flight on one, for the experience.
The very real issue of turn time rears its ugly head on a 753. Taking forever to deplane and enplane is not high on the list of things to do for an LCC. Having two cleaning crews (one per aisle) is also a convenience, unless you're an LCC that only cleans during the down shift.
I stand by my recommendation of the A300-600 and A310-300.
Cheap to acquire, modern avionics, fuel efficient, two aisles.
I've also heard the charter companies are very pleased with their A330s. You can get a _lot_ of uncomfortable seats on an A330.
The 752 is still up there tho, on my list. But you know, Flight International isn't calling me for my list.