Unless you want to make a switch for other reasons, I would just call Comcast and get them to help you lower your bill. I do this every 6-12 months depending on the length of the promotion I have at the time. They ALWAYS have a promotion of some sort and you just have to call to see which ones you are eligible for. Sometimes sticking with the triple play is best, but I have been able to save more sometimes getting promos on each of the services individually. I never do any shopping around, I just call and ask for help lowering the bill. I do the best I can with the first customer service person I speak with and if I think I can get it lowered further, then I ask for the Retention department (where they would send you if you said you wanted to cancel). Sometimes there are additional promotions that the Retention department can offer that the customer service reps cannot.
The trouble with Comcast is that you have to stay on top of your bill and the prices you pay for all the services. If you let it go, your promotions expire and the bill goes up to where yours is now. They "punish" the loyal customers who don't make a fuss. I have to say that I'm not a huge fan of Comcast because of this, but it's easier to call than switch and we don't have many other options where we live (no AT&T). I'd certainly give them a call before you switch to see what they can do for you. If you get it to where you are happy with the bill, then watch for those promotions to expire and call back!