For those of you who complain that basing means that terrain pieces have a step I have a tip for you - chamfer the edges! Crazy, eh?
And yet a step is there. Unless you cut them up to hair-thin edges, while keeping the exact terrain composition both for the table and the building base.
But yeah, i suppose that if you really want to base them, some chamfer could help. Here i'm only discussing the non-necessity of the bases.
As for the "terrain sockets" i really like the idea - and i thought of doing it myself in the past - and it's very well executed, but probably it works better with urban terrain: Especially when you have a concrete table, with "blocks" separated by rims anyway, you can hide the cuts much more easily!
Cheers,
Jack