The original TRX without the safety loop at the top of the strap could do one handle work by looping the two straps together in “single handle mode.” Now, with the safety loop, there is no need to double-loop the handles; you merely let go of one handle and use just one handle. So there really isn’t any more or less variety as a result of the safety loop. The TRX was never designed to be “sawed” left, right, left, right.
If you want to do “sawing” (right left right left) type of work or unilateral work, look into a CrossCore (in my opinion, a superior product, to which I switched almost 5 years ago). That equipment is on a pulley that is designed for lengthening one arm while shortening the other arm. Alternating unilateral rows, alternating one arm push-ups, etc.
TRX is a good product. It launched my personal training career. whether you need the home kit, the pro kit, or the tactical kit really depends on what you’re going to use the product for, and how often. I taught TRX classes 6 times a week for four years and didn’t wear one out. I would guess that my original TRXs are relatively comparable to the P2. I have some of the originals that don’t have the safety loop, a few that have the safety loop.