If you're building a dedicated racer then yes, go to pre-mix. Easier to work on the bike (less clutter) and more accurate for continued high rpm use. You'll need to increase jet size to compensate for the oil in the fuel.

If you're an occasional trackday boy, then stick with the pump. Accurate enough for a 90% comitted track attack, and you won't have the headaches of carrying oil around with you and mixing at the pump during your everyday street rides.

If you'll not see the race track then stick with the pump.

If I were you? Pre-mix Why? Because I hate clutter on the bike, and I can't stand having to remove and refit the 2T oil tanks on any stroker I work on.

Then again, if I were you then you'd be me, and I'd be asking you the questions