Definitely worth upgrading. You can get a C'dale pretty light if you work at it. They are incredibly fast bikes (due to being stiff and not as noodly as some others) and worthy of whatever you can afford to hang on it. If you can fit the stock sizes of a Cannondale, I'm always felt that they are the best value (at any price point) in tandems. They are so capable. You can build them as rocket bikes for tandem racing with lightweight components and wheels. Yet the frames, while lightweight, are so strong that they make great touring tandems as well (obviously with an appropriate touring wheelset), equipped with front and rear panniers. This is where they really shine. Unlike noodly tandems, a C'dale is stiff and you and your stoker won't feel like you are going different directions, at times. Remember C'dale was the original "Bike Packing" company way back in '73 long before they started building bikes (in '83). Most don't know this, but the "BOBish" and Rivendell perspective of building an all-purpose bike actually was ripped off from Cannondale, and specifically the ST series of touring bikes. The Cannondale tandem is completely based on those ST series bikes.

If you go back and look at the early Cannondale ST series you'll see that it was already on the market in '83, '84 (Grant didn't get into Bridgestone until Dec '84, almost '85) as exactly the type of bikes that Grant would advocate with Bridgestone, and later build with Rivendell (save a Cannondale not being boat anchor steel, it is lighter, stiffer, faster, and stronger). The '86 ST is my favorite (maybe, because I own one, but mostly because it was offered in 27", 68~69cm) with just a Grant wet-dream of a build: Front and Rear racks, Fenders, fits wide tires, relaxed geometry and caters to an more upright riding position, Superbe Pro derailleurs (only place Superbe Pro came with a GT long touring cage from Suntour, I think), Brooks honey leather saddle, Superbe pedals with clips (Cannondale branded leather matches Brooks) and straps, Nitto stem, Nitto Ranndonneur bars, Dia Compe NGC cantilevers in black. Just an epic touring do everything bike. The Metallic flake Anthracite paint is still breathtaking after twenty-five years. My favorite part is that the front and rear racks and all three water bottle cages were painted by C'dale to match. I still advocate these as 'grail finds' and some of the best bikes ever made. Worthy of a Joe Bell repaint, and twice the bike that Riv has been trying to copy ever since. My only regret is that Cannondale never made the tandem in the 27" size even though they made thousands of 27" touring bikes (even the LL BEAN/Cannondale ST400 was offered in 27").

So enjoy that C'dale, and have fun upgrading it. You truly have a do anything bike that is as fast or faster than all but a couple of carbon bikes out there. It is a better climber (with a coordinated team) than almost anything else out there, and can outkick just about most other tandems in a sprint. That you can tour with that same bike, just is almost silly. There just is no substitute for a lightweight, strong, stiff, frame on a tandem (or single). I think the extra room the stoker enjoys in the stoker section makes a C'dale a better bike than most other tandems even if it wasn't lighter, stronger, or stiffer.

IMO, often expressed, I think the Cannondale tandem is vastly underrated, and many that have sought the pretense and vanity of a more boutique builder have ended up with "less bike." However, tandems are intensely personal, in fit, and preference. If you can't get a tandem to fit you and your team, it probably isn't the right bike now matter how amazing it is in the showroom.

I'm astonished to read on these forums when people migrate from their second hand C'dales to a Santana or Co-Motion steel tandem. They truly have half the bike, a heavier bike, a slower climber, and a weaker frame. What they loved was the new wheels, new components, and "new bike." Good for you for upgrading your C'dale. Let other tandem teams try out your bike when you're finished, and enjoy the looks of surprise on their faces as they realize that your Cannondale is something special.

I lost money in Cannondale the corporation (ticker BIKE) after Joe Montgomery used corporate monies to secure a multi-million dollar personal home, prior to their bankruptcy. So while I think Cannondale the corporation was a horrible horrible company, their bikes were world class (at least the tandems and ST series touring bikes).