Good work

Thanks for sharing!
What was the final yield?
As for the original question, yes using both xylene or toluene will increase yields as they dissolve dmt better (but also other impurities as you said). I dont know if anybody ever tested for differences in xylene or toluene. I already used both (though in different extractions) and they both worked perfectly fine.
Do note that they smell horrible though, specially xylene imo (toluene smells more 'sweet' but also the kind of sweet that feels like its destrying the brain cells

). If you use any of them, rather salt out (with FASA, FASW or vinegar), evap/dry that and later freebase, instead of evaporating the solvents. This way you can reuse the solvent and its not so nasty with all that evapped solvent.
Or, as I prefer, use limonene, which is also a pretty good solvent and smells great, and then salt also (FASI, FASW or vinegar).
By the way, how many and how big pulls had you originally done on the A/B before mixing with the 'spent' bark?