You probably couldn't find a better place to ask, but you're a bit out of luck with the answer. That question has been debated several times here, a search will no doubt turn out lots of these threads, and as one can guess without ever reaching a conclusion. Ask it on the SH3-board and not surprisingly most people will say SH3, ask it on SH4-board and the answer will be SH4. Some like the mom while others prefer the daughter.
In this case you have the opportunity of trying them both out, somewhat of a rare situation in real life, so I suggest you use it and see for yourself
