#2 was at my house last night. Although I'm not a Concert fan, I do appreciate good work, and Collings has it down. It has the right amount of everything that a Concert should - little more resonance than a standard, more complex, not as big(and I don't mean size) as a Tenor, not tinny like a standard. Bill definitely did his homework.
The frets were leveled to the hilt, but were rounded nicely, as well as having the ends dressed nicely - although I'm a fan of binding the F/B, sort of a mix between KoAloha and G-String (bound, but with a bevel).
Quality? Don't ask. You don't have to.
The only drawback was the strings, but that's me. What strings would I put on? I don't know, because I don't play concerts. Of the top, probably Pro Artes (but they may be a little too big), or Worth. I would certainly try Ko`olau for #2 Collings (mahogany, satin finish). Honestly, I don't think it would matter much.
Strings will not make this instrument, although the current strings seem to be trying to squeeze something out of the instrument that it doesn't need to - sort of like putting NO2 on a 4 cylinder import to make it go fast. What's the purpose, you're still missing half an engine anyway? Given a V8, you don't need the nitrous, and neither does the Collings.
Whomever gets this will not be disappointed. For the price, I'll take a local factory anyday (and twice on Sunday), as that is the sound the Collings emulates anyway - of course, it would not be their #2 instrument.
-Aaron