I'd stick to the leather. The BMW leatherette is good quality but ... it's plastic. Leather smells nice and the experience is much better.
And as noted you can't get lumbar support without getting the 'premium' package which includes leather. Worthwhile package to have.
2011 BMW 335i E92 - Le Mans Blue, 6MT, M Sport. JRZ RS Pro, Quaife LSD, BMW Perf Exhaust