As others have stated it depends on who it is . I run stock engines because i don't see paying 80 to 100 bucks for an extra minute or 2 of run time , but i am not that serious about r/c . I was heavily involved with motocross for 10 years trying to get my son to the pros . After he had a career ending injury last year we decided to try r/c . We have fun but just aren't that serious . If you need the extra run time go for it .