probably not very much NOTICEABLE real life difference in performance.
Benchmarks may show some diffs, but often these diffs do not really transform to NOTICEABLE diff in real life day-to-day usage. Infact I see litle diff between by 256 gig M4 (in laptop, I5-2410M) and My 256 gig 830 in desktop (i5-2500k).
Not sure on reliability/usere satisfation between the two. Performance diff surely not worth 65 Bucks. I was Lucky, bought both My 256 m4 and My 256 gig 830 for $180 (USD, newegg).
Note above is latest, it's for vertex 4, BUT includes the 830 for comparision sake.