I agree with the statement that the filters are worthless. In my case they sure are. The Coloplast Sensura has a filter at the top and I even asked my supplier..."What the heck are they good for when they clog up with poop within a matter of hours?" 
He couldn't even answer my question..lololol. Oh well. I don't know how you would burp a one piece, two piece I can understand, but the one piece only has the bottom.
Oh...another thing I did not like about the Hollister and that is the bottom where you empty it. Very inconvenient. Coloplast is MUCH easier.
You will feel overwhelmed when you come out of surgery and see all the "stuff". I will not go into detail. Just take one day at a time. I can remember looking at my bag for the very first time and thinking..."How in the heck am I EVER going to deal with this?" Time has a way of being very beneficial. God knows I had my post op blips, but I would do it all over in a heartbeat compared to the suffering I endured during my UP (you remember my problem was the rectum..proctitis) days. I honestly can say, I don't think I would be here today, at age 66, living life to the fullest and enjoying every moment God gives me had I not had that operation.
OH...make sure your surgeon is a top notch colorectal surgeon. Even though you are going to have just the one operation, you want to make sure he does a superb job on that stoma!!!