Guy,
Some time ago there was a discussion regarding 180mm lenses and talk turned to the Sigma 150mm. Although if memory serves me correctly, a couple here were not overwhelmed with their Sigma 150 in general (I think they might have been referring to the non OS version)....yet in general most everyone has been overly enthusiastic with the non OS 150 macro and I certainly am on virtually all bodies I've used it with. As a 1:1 macro, it was as good as any out there and at infinity it was a competent-strong performer. Now here's the catch (rub). I tested a couple samples of the newer OS version which is heavier and for whatever reason, I was less impressed and I've spoken to other non OS 150 owners and they felt pretty much the same.
The OS version just seemed a bit lackluster against the older non OS version. Not bad mind you, just lacking that something extra. If one never had the non OS lens, then maybe the OS version looks exceptionally good as many reviewers have exclaimed, but unless the OS version has been tweaked (which it very well may have since it's introduction), I've been sold on the lighter more travel oriented non OS version even though it lacks "OS". Just as a side comment, my non OS lens performs quite well with Sigma's own 1.4x and only barely got by a pinch with their 2x, if one must take the shot. Nikon converters don't mount on this lens without modification.
I overwhelmingly prefer the Sigma 150 over the Nikon 180mm by a wide margin, having tested both simultaneously.
***P.S. Guy, buy the way, after your trip to NY, what have been your conclusive thoughts regarding the Tamron 24-70 f2.8 lens you recently obtained?
Dave (D&A)