Good choice! My Baron was converted from caliper brakes to Avid Mechs, so I can't help you on the Maguras. I'd go so far as to say that the Baron wasn't really designed for calipers. Discs are what fits and work best. For options and accessories, I'd recommend the carbon seat option. The fiberglass (polyester) seat is heavy and flexy, and not as durable either. I punched a hole completely through one at the top mount, and cracked the replacement before buying a carbon one. Optima said it was just a bad batch, but I don't think so. The must-have accessory is a Carbon Fastback hydration system. It holds a 100oz bladder along the left side of the seat, and also includes a small tool bag that fits behind the seat. Gives you lots of storage without resorting to something dorky.