I like what I am hearing. I would be running the 300sxs kit from KTM hardparts w/ headmod ,taperbore carb w/ dial-a-jet, and an sx ignition on an 08 250 lower end. The clutches are very good on these bikes however I would run a core EXP by REKLUSE. If I can do this with my primary bike and not have to buy a four stroke I am $$$$ ahead and the kit starts to make a lot more sense. You should put a link to your idea on KTMTALK, lots of good people on there that buy a lot of products.
The 300 works very well with the MH kit, it made my 525 look pretty stupid several times. I sold my 525 and picked up a 300 and will be running my MH kit on it unless I pickup a CR500.