I think that's pretty much it.My understanding is that the direct upgrade to a Shukan would be a Rod Bar, rather than the SM.
The Supermix has a much softer tip than the Shukan - so is musch better with soft baits. I use an 8'6" Shukan most of the time, but have tried the Supermix 210 and I think a 270 while messing around. Being used to the Shukan, the supermix does feel very soft and you'll probably think it's not so good for topwater stuff. Other than that though, it'll do it all brilliantly.
Rod Bar may be a better option?