Absolutely leave it on there,Ive only heard of 2 failures in the history of the Mikuni oil pump.The one failure was because the guy put motor oil in it instead of 2stroke.Why mess with mixing,fill it every time you fill the gas tank.
Take a look in the mini forum, I think there is a thread in there from a month or so back about eliminating the oil injection on one of the little bikes (Suzuki jr50 maybe?). Same principles should apply here I would think.
i have a blaster and left it on there. just make sure you keep an eye on it. sometimes if i go for a long ride i mark it w a pencil to make sure it is always working, ive had 2 blasters and never had a problem with that.
Just make sure you don't mix your oils. Older mineral oils will co-agulate if mixed with new, and block the thin feed pipe. To be sure maybe flush it right through if you change oil brand/type