If she has been fine with the last 3 bottles then she will be fine - she would of reavted to the first bottle and cow and gate is generally very good a I use it and love it.
I switched straight from SMA Gold to Cow & Gate and had no problems doing that. Unfortunately the milks for digestive problems are very thick and you would probably need a fast flow teat. For reflux I recommend stopping her feed every 40/50mls and winding as this seems to stop a big throw up at end of feed. We did this with Maddison and now she is hardly ever sick and we no longer have to wind her every 50mls