The 390/Boss isn't really a soft jib binding. It's a mid-flex binding which means it is decent for any type of riding. Sort of like a jack-of-all-trades, but master of none deal here. Well, it is the master of groomers
If you do a lot of steep runs, pow runs, and just plain fatty carves all day long, then the Targas will be a better choice.
If you hate bending down to strap in all the time or your mountain is actually a hill, then the Flow NXT-ATSE is a great option. It is also good for reducing foot pain greatly as the cap design gives your feet an even pressure distribution.
I run the Bosses on my Proto which is the same flex as the SL. I do all-mountain freestyle runs with a little park for smaller kickers and they rock in those conditions. I also had them on my Turbo Dream in Tahoe powder and I did fine with them.