On Wednesday, December 7, 2016 at 3:54:53 PM UTC-8, Thor wrote:
I'm looking at buying a ASW 27. The ASW 27 are usually 15k less than a ASW 27B, WHY?
Does the ASW 27B have an performance advantage over a ASW 27?

Not performance, but other changes:
The B model offered an optional tail ballast tank, unavailable on the original.
The water ballast dump handle was relocated on the B to a more easily reached and less likely to be elbowed position.
There is more Carbon in the B model fuselage layup, making positioning antennas such as FLARM or TXP more critical.
As Hank mentioned, Schleicher wing tanks are more likely to cause waviness of the wing skins than ballast bags. Or perhaps most other manufacturers' wing tanks?
Also noted previously, the newer winglets work better. There are still a couple of 27s left with the old stubby winglets, but low speed handling is improved by the Tech Note 4 Darlington or Maughmer mod, or Nixon, Nelson, etc. winglets.
If you have to do the Tech Note 4 mod, make the tip skids taller at the same time to keep the ailerons out of the dirt, and include tiedown points in the tip skids.
Jim