ATC SM-150 Midrange

I'm a newbie here, so please excuse me if this subject was broached here before.

Currently I own a pair of Martin Logans els, but I'm going to sell them as I feel I need to go back to 'conventional' speakers...
I'm going to build a new speaker using ATC SM-150(S?) I have few questions about it :
- in the first place, is it WORTH the money (in Poland, it'll cost me about 950-1000$ per pair)...?
- what should be REAL bottom crossover point so that it doesn't sweat...?
- will it sound ok with ScanSpeak D2010 or maybe there's any other good, fairly cheap tweeter that I could use instead (up to 200$ per pair)...?
- what (also, fairly cheap - 500 $ per pair) woofer should I use...?

And finally, my idea is that - will it make sense, I mean using ATC
with cheaper drivers like SS D2010 for example...?