If your budget is limited to an A3 model, or that’s all you think you need, look for one that supports roll feed to get the most out of panorama format and make sure you can get a CISS to suit it.
Yes, Pixma 100 is good still now, I have a few guys in the office that are using it. There are a lot of new models on the market that have more features and are printing faster with a higher quality. So if you will decide to change the printer, I can suggest you to check for a new one on Palmgear website. They have a list that includes the best printers for different segments and each one has its description. Personally I am choosing printers with the help of this website and I was always thankful.