The initial reason for considering a tarp was for weight savings and simplicity. I was also curious about it after reading people rave about the benefits of a tarp and floorless shelters. I guess I was trying to understand how to go about setting up in the rain, if there was something I was missing. I can see how a floorless shelter would work in the rain if there was grass, thick duff or dry ground to begin with upon set up, but it just seems like the potential for a wet filthy mess is too great for me. I guess I was missing nothing all along, and as I suspected, it is in site selection. There is no real magic to it.
I sometimes go solo packing and have the flexibility to camp where ever I decide, thus I have more flexibility in site selection. On the other hand I often go with groups and have to camp in designated areas based on inflexible group plans. This means a camp area that can be devoid of grass and vegetation, under dripping trees and plenty of bare dirt which is either mud or can turn to mud in a downpour.
Thanks for your thoughts on the matter. I guess I will not try to fix what isn't broken, and continue with the Squall 2.