Absolutely, I must say the IXEG 733 has (IMHO) the most real engine sounds ever developed for an airliner on X-Plane (and maybe other sims too), the Flyby engine sound, specificaly... is the most realistic I've ever eard... I hope that won't change on FMOD transition.
I second this in every word! An upgrade fee, should be completly acceptable, considering the time and resources invested in, and I was expecting something no less then 20 or 25 USD, generaly charged by other devs... so paying only 15 bucks to have a top quality aircraft (my favorite boeing!) to fly on XP12... I say it it too, looking forward to friday!