YS engines are not for everyone ,They do tune different from the others.IT does take some reading and hands on to get the engines to preform correctly .If your used to just setting the top and bottom somewhere close and go fly ,I would say the YS is not for you .Yes they do take a little longer to get in tune,maybe 5 mins 10 at the most but once its there its there But the 120 YS in my mayhem has never once died in over two yrs of flying and at around 300 flights I would say thats a good track record.
If a YS engine is dieing its either not tuned correctly,wrong prop size incorrect plumbing to the tank or the wrong tank itself the wrong or a bad plug or it has a mechanical problem of some sort .
I had a 63 that I just could not get to run properly sent it back to YS 3 times ,finally they sent me a new engine ,but by that time I had had enough and sold it unused .
With the exception of this 120 thats in my Mayhem I have had them all die at one time or another ,usually because of a to low throttle on a violent move .
Anyway I will agree the saito is more user friendly when it comes to tweaking the tune ,but still wont hold a candle stick to the preformance of the YS ,plus theres the tank issue try putting it on the CG running a saito WO a pump and see how long it runs if it runs at all.

BTW I do own several Saitos so its not like I don't like the engine or anything and they all run flawless, I am just giving you a fair example of the 2 engines from hands on experience

I am sorry about your buddys plane ,but here again if they have a hint of a prob on the ground the air isn't going to make it any better and usually ends up in a dead stick and maybe worse.