basically, the low water difficulty goes in stages... the first 5 miles until below velvet falls are the most technical and demanding then it drops down another notch in "ease" until the pistol creek/indian creek area then it's pretty straight forward for any heavier loads for any competent rower on a low, water technical river.
an IK seems like overkill conservative to me if you go off the top. lightly loaded rafts are fine...again assuming competence in rather technical water, a willingness to get stuck in a few spots and nail some rocks pretty good.
personally, if people are leery of the upper 25 then just fly in people and all, avoid the "stress", enjoy the float,see how that goes for your group and then be able to make up your own mind for future trips on tackling the upper 25. no shame in that. at low flows, 75 miles is a nice casual pace with time for side trips, fishing,ect. anyway.
also, there is a dvd available through adventure sun valley on the river run off the top at 1.70 you can buy for your own reference too. keep in mind cameras always make the gradient look a little mellower than it really is though.
ultimately, it's for you to decide though. nobody here knows your skills or lack there of for you and your group.