Mag couplers have their place in a three gun match. The Firebird coupers are awesome as a mono pod.
I use the 48 round mag for big run and gun stages. I use the 30 30 coupers for stages that require a reload or have cover that I can shoot off of. The Mono pod ability is far more stable than a single mag. I use the 20 30 coupler when there is a very low port I need to shoot under. Using the coupled mags is nearly as good as a bi pod.
Pat