Looking for feedback/reviews from folks with the SpeedBooster EF autofocus adapter and autofocus lenses. I'm wondering how well the AF works, and if there are any lenses that have proven particularly good. I'd be particularly interested in experiences with fast primes, and standard(ish) zooms - e.g. 35/1.4, 50/1.4 and 17-50/2.8 or 17-55/2.8. Thanks!