KEH in Atlanta has some great deals on used cameras. I use them to trade my cameras in for a newer model when there have been some major improvements. I started with a Canon 10D, then a 20D then a 40D and now have had my 7D for about 3 years. It takes amazing video. I bought an external mic(Rhodes) and the results are amazing. It is a large frame camera but I have big hands. The T series cameras are smaller but are great cameras. Just check the feature set so that it will do all that you want. As to Megapixel ratings, all of these cameras go beyond what we can see. High megapixels offer the professional and artist photographer many advantages that the rest of us will never use. If you consider a used camera I suggest you call KEH directly and speak to one of their reps. I have always found them to be honest and knowledgeable. THey care about their customers.
Good Luck!