I just bought 2 boxes of the 129gr. And 142 gr. Can't wait too try them out. Friend of mine has tried them on hogs and they expand very fast at close range...blew a hole about the size of a cantaloupe in it. Other than that, that is all I have heard/seen performance wise.
Not a WSM, but I've got a couple different 129 loads sitting on my bench waiting to be tested as soon as the heat drops below 800 degrees. I'll try to remember to post my range report.
Like tobacco road and johthomps, I've got loads waiting for the temps to drop just a tad below 104 before trying them out. Will post when I have a chance.