I would be reluctant to use WLP029 for Alt though, because the viniousness that I love in kolsch* I don't like in Alts. I prefer WY1007 (German Ale) which is very clean, and responds very well to cold-conditioning.
My thoughts too. Kolsch yeast is so distinctive (to me) that I don't feel you're making an alt if you use it. Not saying it won't be a good beer. But 1007 is so reliably good and authentic for alt I can't imagine not using it.
Ok got it. White labs and Wyeast both list their kolsch yeasts as choices for Alts which I was going in that direction. Since I have the kolsch finishing up I thought I might as well reuse the yeast. Sounds like I will end up with an Amber Ale fermented with kolsch yeast...
Based on the basic ingredients description for N. German it seems like there can be quite a bit of variation:
"Typically made with a Pils base and colored with roasted malt or dark crystal. May include small amounts of Munich or Vienna malt. Noble hops. Usually made with an attenuative lager yeast".