I'm interested in this too!
I've recently gone over to the SR version too - first batch was Bolamyn SR2x500mg. Both the leaflet and the pharmacist/doctors instructions say to take both tablets with or after my evening meal. (Previously 1x500mg 3 times a day with meals).
This time round they've given me Metabet SR - (our pharmacy seems to change brands on some prescriptions depending on which way the wind's blowing!!


) - and the pharmacy label also gives the same instructions as before, but the manufacturers leaflet says additionally that the doctor may recommend that you take the tablet twice a day.
It would seem to me that it was more logical to take them twice a day, as at the moment I'm going down to a much lower reading 3-4 hours after my evening meal, and then have gone up again the next morning and stay that way most of the day... I'm going to ask for clarification when I get to see the practive diabetic doctor in June - first appointment with him instead of my usual GP.
Robbity