No matter what people tell you. Trust me, you will never go wrong with an OS. The .46 is a great second engine that gives you the largest breadth of 2nd or 3rd planes to choose from.

The Dazzler is 4.25-4.75 lb ....and its engine rating...
Engine Required: 2-stroke .32-.46 cu in (5-7.5cc) or 4-stroke .40-.52 cu in (6.5-8.5cc)

The OS .46 is a perfect engine.....with that combination you will be able to hover and pull into a vertical climb from a stand still. Just remember to use a little throttle managment and use your Avistar to practice throttle managment now so you will be ready. Practicing flying your Avistar at 1/4 throttle, 1/2 throttle and transitioning between these combinations. At full throttle, the OS .46 is going to pull the Dazzler like a bat out of hell so you will only need that kind of speed or power occassionally and most likely you will be flying at 3/4 or less throttle.