Firebarriers.co, Fire Barrier Domain Name as Good as .com?

Fire barriers are a a piece of material that you use to protect areas of your home from fire. Its a competitive market in some areas and a company I have been working for was looking to move their site up the Google rankings.
To help with this we set up a microsite with specific copy aimed at the key phrase and used the domain firebarriers.co. This is the first time I have used a .co domain as really a replacement for the top level .com, but in theory we should now also be thinking of .co in the same way.
So what has happened? Over the last couple of months the site has really struggled. For some reason the home page didn’t get picked up by google despite frequent changes and a secondary page really struggled too.
Despite the competition I really would have expected a .com to do much better, so even though I’m not testing side by side, I have to conclude that the .co domain is not given equal authority to the .com domain.
Let me know if you have similar experience, but in the meantime if you are interested in fire barriers and your in the UK. Try firebarriers.co, they really know what they are doing and seem great to deal with.