I think the only reason for doing a steep approach is to keep above the demarcation line (where the laminar flow over the mountain feature turns turbulent) but I would always go for a shallow or even level, curving if required, approach staying in the updraughting air. You use less power and have a safe escape route if you don't like it. Oh and do a power check at altitude before you commit to the site just in case the engine(s) don't produce what they should.