well yea, i mean, its always to see what you actually feel is better, though i can just give the analysis, but if you can make her a better character like this then go for it.. i mean i think that is what Sled did, so you can kind of ask his opinion on the matter...
the idea of HisuiKohaku team is Kohaku gets the benifit for Hisui as assist.. so its a better character choice then say using Kohaku by herself.. cause obviously her team power play boosts her up much further then by herself
Hisui by herself is better cause of use of Stuffo as her ranging ability, but using her in a team takes away that but gives her a medicore support, so you see the comparison here?
both single characters Hisui and Kohaku have their ups and downs, in team play it doesnt mean both character gets the bonus