We have a combo and did have occlusions when using the flexlink plus cannulas, but since moving to rapid D link we have had no trouble at all. We do get the odd bubble now and then but they are quite rare. As for gushing blood, well, we have no problems there either, I don't think this is down to the pump anyway but rather the infusion set that you are using. I don't know what length needles you are using but we use the 6mm and my daughter is only a skinny little thing, maybe you could try a different length needle or a different set.
Harry