I loved my 6.0 and It's hard to make a comparison in a brief statement. In an effort to make a quick reply I'm going to sort of ramble for a minute....

The 6.0 is taller off the water and harder to get back on than the I20 if you've found yourself in the water. The 6.0 has a smaller trampoline and the cross-trampoline jib wire is called "the cheese slicer" for good reason! The 6.0, in my opinion, is a 'bloodier' boat and there's more to scrape and scratch yourself on. That being said, because the 6.0 sits a little higher off the water it will stradle waves a little better. The I20, offshore in waves, will occasionally smack the rear beam on a wave - and it can be quite violent (back me up here Dave!). The big jib on the 6.0 makes it a high reaching monster and I believe the aluminum mast, which is more flexible than the I20's carbon stick, allows you more opportunity to depower. The 6.0 won't point quite as high as the I20 due to the large jib. The 6.0 is a great machine offshore but it doesn't have quite the forward buoyancy of the I20...in moderate offshore chop and the right wind angles, the 6.0 is probably faster. The I20 has more reserve for the heavy stuff.

The 6.0 is more forgiving at the helm than the I20. I remember the first time I helmed the I20 after having a 6.0 for a year or so...The I20 was shockingly twitchy and I almost put us in the water the first time I trapped out. To that point, the I20 is less forgiving and has a habit of punishing the crew for not quickly reacting to a puff. If you get knocked up hard (when you're trying to react with downhaul), the rudders will stall unless you ease the mainsheet. However, I understand that this has been made better with the new rudder profile.

I like both boats very much and both have their strengths and weaknesses. If I were racing on lakes and had a class to race in, I would prefer to stick with the 6.0. The 6.0 is a heavy handed speed machine...the I20 is a finess speed machine....kind of like Nascar vs. Formula 1.