Rexler, i think if properly supported, is going to be a great Counter to Decimators.
Give him a HLC, FCS and say a Shuttle with Fleet Officer nearby and watch those big fella's cry.
As he has been brilliant in Epic, I imagine this will be true.
In epic play, with access to Comms Boosters (because hopefully an imperial huge ship is on the way), Fleet Officers and other shenanigans, Defenders will be murderous. Unfortunately, -as I always said- stock Defenders are pretty incomplete in all aspects except basic stats, so they require too much upgrades/support to truly perform, which almost auto-excludes them from normal tournament play.
The moment we can start to play epic tournaments, I'm sure we'll see more of them fielded. The defender is a nice platform to be supported, but not to play on its own.