I never even tried to go back and forth with the snowbike thing...it's a cool idea and I know some do but for me thats just not happening. We go on droughts sometimes for a few weeks in the winter or get rain instead of snow...I don't want to miss good conditions dirtbiking, and I don't want to miss good snow conditions either. If I was going to use my bike for both this is what I think I would do.
Buy either a KTM or the Yamaha...as stated electric start and FI must haves.
I would have an extra subframe with airbox ready to swap back and forth with whatever mods were necessary to get the airbox to work for snow...I think if you are Yamaha you can skip this step, not sure.
I would have an extra front brake master cylinder leave it hooked to the snow kit and my other one hooked to the swingarm shock setup.
I would either use an airpro set up or have an additional set of forks all sprung up for the snow bike.
If you had all the pieces separate to go back and forth you could swap in under 2 hours I think, that would be required for me, I'm pretty into my moto time, especially the chocolate cake, and I have become a junky for the snowbike...for me I just have to have both.
I also think the "you get 2 for the price of one" is a good sales tactic, but the price I see on used sleds looks like I could have a pretty decent sled and a pretty nice dirtbike for about the same price as a well set up snowbike. Don't get me wrong I love the snowbike and I am better on one than I will ever be on a snomobile but the more time I spend on a snowbike the more I am thinking I might want a sled too.
Better get back to work to pay for all this chit.