The commonly used version of sidestep reads as follows (taken from the MBBL site):
"Side Step is changed. Side Step reads for PBeM: A player with this skill is so quick that he can frequently step out of the way of a block. As a result, he may completely ignore PUSH BACK results from the block dice, and a KNOCK DOWN result always knocks the player over in the square he started in (ya just clipped him). In addition, this means that the trait Frenzy will not work against this player as a Push Back result indicates that the blocker/blitzer missed with his attempt to hit the player."
That makes Sidestep almost as good as Stand Firm ( you can never be pushed into the crowd ), with the exception that you don't get the 'free dodge' . (Countering this however, Frenzy doesn't work against Sidesteppers).
Now consider that Stand Firm requires a double to get, and then is only accessible to those with ST access. Sidestep however, is available to anybody with AG access and anybody at all on a double. So we have an easily accessible skill that's damn near as good as a ST only trait.
I found it a particular problem facing multiple Sidestep/Stunty players.
Consider this (simplified) diagram:

B is the ball carrier, A and C are Sidestepping Skinks/Gobbos/'Flings.
Now on the tabletop, a Blitz either with the ball carrier or from elsewhere on A or C (or indeed a Block from another adjacent player) which results in a push or Splat/Dodge leaves (with a follow up if Blitzing out with player B) one dodge roll to get out. The same result in Pbem leaves a dodge into a tackle zone and then the same dodge into a clear square to achieve the same. Now if player B were to be blitzing out, a clear Splat! on the tabletop would allow the follow up and away without rolling the dodge. In Pbem A or C would go down in the square they're in and you still have to make that dodge roll (and effectively lose a square of movement in the process).
My thoughts: the Pbem version of Sidestep is waaaay better than the tabletop version, is damn near as good as Stand Firm and is much more readily accessible. As such I believe it is overpowered (particularly when combined with Stunty (and let's face it, it's a commonly taken skill for Stunty players on a normal roll!) and used in multiples.
Thoughts from Pbemers?