I recently picked up a pair of RS334 towers. They have surprisingly impressive bass response. I've never experienced the amount of low end that comes out of slim towers such as these.
On the opposite end, the treble can also overwhelm at times. Lesser quality sources (high bit rate mp3) sound particularly shrill on my Bostons.
Anyway, I suspect the RS326 are similar sounding, but with even more low end output. I honestly don't think the RS series needs more 'low' over what the 334's provide.
I suppose for dedicated 2ch listening, the 326's may add a touch of value, but otherwise, I'd recommend the cheaper 334's for those interested in Boston.
For the right price (not retail) I think the RS line is a middle of the pack speaker. I liken them to NHTs in many ways.
If slim tower, solid low-end performance is tops on your list, they deserve a listen.