I was seriously thinking about getting the new TD-1KV, but the TD-4KP has a much better sound module. It also folds up into a 12″ x 20″ package, so it’s very portable. I miss my TD-12S, but it’s back in Cali and I didn’t want to ship it here–not that I really have the space. It’s a lot larger than the 4KP.
I prefer the 12S’s mesh heads and it will take getting used to the 4KP’s rubber ones. I may replace the snare with the mesh head pad at some point. The sound module is pretty good and it’s very customizable, something the 1KV is not.