On first review, this might seem like it favors the lamers, but I think the top players would benefit more from 5 secs, and I don't think the scheme needs more division between the top players and the newer players, bng has a very steep learning curve, one of the hardest outside of ttrr. Then again, 5 sec could make the scheme more fair in that a map with one side with better hides than the other would be more or less negated because more hides would be reachable with 5sec nades.
That's what i'm thinking, Classic League schemes are easy to learn the basics and get the job done, but takes a long time to really master everything.
This would definitely benefit top players more, it gives us an extra shot that can reach places other shots couldn't(and it's very easy), i'd be worried newer players would just risk sitting too often because of the extra fuse.
This is me being honest, can't think of anything else though:
Pros:
Gives good players a few extra shots(but they don't really need it)
Makes the rules shorter/simpler
Cons:
Higher risk of sitters
Gives players another reason not to learn advanced BnG shots