Yesterday I SRT'ed up using my VT and pantin. Today I used my pantin, CMI ropewalker and CMI expedition ascender. Ascending on a VT is fine assuming its not too long to grab. The problem with your hitch not grabbing isnt that its being used in SRT, its that the tress cord is too long. I have also ascended many times using only the CMI rope walker with or without a hitch backup.