+1 to everything Jason and JCAT have said. Both honest assessments that mirror our own experience.
Jason's point about the dirt/mud/water on the bottom is pertinent - we use the same Ultramesh tarp as KB above, but find that we still need to towel down the bottom PVC floor whilst packing up. Even if it's a dry stay, the PVC will pull some moisture out of the grass/ground and you always end up with sand/leaves/mud stuck to it. Whereas with a hardfloor you've got two things in your favour : the floor is typically raised off the ground as Jason has said, plus you don't care if it's wet anyway because it's on the outside and not touching canvas.
One thing we noticed when camping with Teabag once and his KK - his took longer to set up because he wanted to get it level and right. CD in his Trackabout was set up much quicker, because it didn't matter so much about the level. However when it came pack-up time, Teabag was done in a fraction of the time. . But as I'm sure I've said before, my experience is that the pack up time of the camper tent itself usually only accounts for a small percentage of the total packup time once you factor in folding chairs, tables, portacots, etc.
To me, the limited space in a hardfloor counts it out for us, and we've only got one little one. The 10" tent on the Extenda suits us perfectly. But that's because we use the tent as a room for playing in, organising clothes, portacot, portapotty, etc. If you can live outside during the day and only use the inside of the camper for beds/sleeping, then you can get away with a much smaller setup.
The extenda-type campers (any brand) are great - you have to deal with a longer trailer, but the extra versatility and storage more than makes up for it in my book. If I were to find myself on a track where the extra length became a real concern, that's a good indication that I don't want to be towing (anything) on that track. Example - I know you can drag a camper over the CREB - lots here have done it. Personally, I wouldn't - it's just not something I'm interested in doing. Hence the lower offroad ability doesn't affect me one bit. You and your requirements may be different though.
Just to touch on the "quick overnight stop" point - ours is very quick to set up for an overnight stop because of the tent design. Assuming the weather is compliant, we don't need to peg anything down - the tent section is completely self-supporting. If left hitched to the vehicle, you can be set up amazingly quickly, and packed down almost as quick. I would still expect a hardfloor to beat us, but it wouldn't be by much. Certainly either one of us would be significantly quicker than someone who needed pegs (or complex internal poles) as well. If we were expecting a lot of wind or rain I'd probably peg ours out, whereas the hardfloor has the upper hand again because they don't need pegs at all.
Good luck!
Matto
