Well im just about done with the build up of my new MBX5 kit

. All I have left now are the servos, fuel tank and SELECT a engine. I narrowed it dow to these 3..
1. RB WS7II
2. O.S. VZ-B
3. Sirio BR-PRO
I really cant make up my mind, so i would like to get some comments from u guys on these engines. No matter what it will surely be one of the 3. The O.S. VZ-B was my 1st selection but i hear that the metal the piston is made from makes the engine wear down prematurly

. Has anyone else heard this? Or does anyone have one is having no problems with them. My hobby shop said that there is a rumor about it but its not true and people just arent breaking them in right.... Your comments and facts will be appriciated...................