there maybe changes within the Monoprice Monolith line up. The Encore T6 and B6 no longer on sale (although they still have the C6 on the site).
I'm unsure of where the appeal of the THX-426T/420T lays. For 2 channel, purely music listening they are going to be good, but would they appeal to a music audiophile, who do not tend to be as price sensitive?
For home cinema, most people will have a sub or more, so the appeal of a large tower in this instance is questionable. And if that person wants a tower speaker just because, they are likely, again, to be less price sensitive.
For openness, I'm running Encore T6 LR & 365C with Monolith subs and Encore B6 as surround (although I'm toying with running C6 as surrounds).
The reason for the T6 LR as opposed to the 365T is that they sound great, are cheaper, and were further reduced by 48%