Yeah, the slippage with a synthetic is what I was guessing. I suppose motorcycle-use synthetic is designed to avoid that.
As far as oil that I use now, its automotive petro. I use Castrol 10w-40 here in hot-ass Florida. Many people would say its too thin for 100F summers, but on a new engine it wont do any harm.
As far as waiting the 5k miles, I will. Im not as familar with v-twin engines, or motorcycle engines in general as are many people on this board. If flipper says that 5k miles isnt necessary, Its probably true. Ive worked mostly in the automotive field in my mechanical life, and have only done mechanical repairs on motorcycles that are common to cars ((ie pistons, rods, heads, brakes, etc.)). Synthetic oil is a marvel, but only when used properly. Ive known too many friends/customers who have gone to synthetic ((in cars)) too quickly and have experienced the ill effects of such.
Suzuki defines the break-in period as the first 1k miles, with the first 500m being the most important. Theoretically, you could switch over to synthetic or semi-synthetic after the first 1k miles. The sooner you get a syn oil in your engine when its ready to use it the better. But if it is indeed ready for syn at 1k, Im more than willing to wear the engine another 4k miles before using it just to be sure.
Mine is only an opinion, and as I stated, probably not as skilled ((for motorcyles)) as some others in this forum ((ie flippers post)).
Au revoir mes amis