Well, technically, silicone hoses will expand less and adhere better to metal (at the radiator, pump, etc. fittings).
But it's mostly aesthetics.
Price for the coolant kits range from about $100 to $300, depending on the number of hoses (I'm getting this from looking at their US dist. sites for their other bike kits). I think the speedy would need 5 hoses, from my recollection of looking over the engine, which based on their other kits of that size would be $100-$130.
I don't know for sure, though, like I say I'm just looking at the US distributor sites (sporthoses.com). They've got some pics up, too, of both the car and the bike kits.