YES the Jett's are as good as you have read...

The 4 stroke vs 2 stroke for speed argument is a sensitive one, tread lightly---

You are talking about a YS-1.10 now, they can be made fast on a certain type of airframe but it depends what you have in mind...

Honestly, I would decide what airplane I want first then research engine options.... The Mustang Saito combo. does not compare to a properly set-up quickee or delta, trust me