If he's as good as the OP says he is, it would take him a day to adjust to the multi...probably less. I have 4 sticks strung right now; in two of them I'm comparing Gosen with S-gut. In the other two I have Scorpion and SPPP Hexa. Yep, there's a distinct difference between the two, but when you have sound fundamentals and good technique, making the adjustment isn't that big of a deal. It's not like trying to wean someone off intravenous pain killers or something lol.
Need help finding lost dog: walks with a limp, recently castrated, can only see out of one eye - answers to the name, "Lucky".