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 E92 335i, 6MT, M Sport, Le Mans blue - Michelin PSS, Quaife LSD, JRZ RS Pro, JRZ camber plates, Eibach ERS, full M3 susp, custom toe arms, Powergrid end-links, brake ducting, SS brake lines, UUC SSK, ETS FMIC, ER CP, Perf. Exhaust, work by VAC Motorsports