a friend lent a ro tour 2.0 my brother, who tested it with an isospeed 1.20mm as a muster but less tense anyway. (26kg), I hit a few balls this morning, compared to my 690 MIA pro tour I toruve them a little drier, less powerful (necessarily 630 Vs 690), but not unpleasant .. but I find (maybe biased by the habit of the 690 in L2 and karakal PU Super, there it was L3, leather grip and sticky overgrip) .. but I found less comfortable and less sensations ...
but I think that with such a small frame, and 18/20, you should not hesitate to go down in gauge, and use 1.10 in poly, or 1.25 in natural gut.