The Walkers do make a difference on my dynamic system as well, although I think they're expensive for what they are (not the improvements). The designer of my speakers did a measurement at the tweeter with the HDLs in and out of the system and there actually was a measurable smoothing of the treble output. The room lenses didn't work for me, but my system is almost an omnidirectional one, that probably has a lot to do with it; on a more conventional speaker system my result may well have been different.
