My product will definitely not be a 100% copy of basecamp. Basically I shall take their features and philosophy and built it in my own way. And to keep things simple at my end there will no Ajax. This will alone make my product substantially different from the 37s. So I don't think it is some sort of rip off.

I think I shall be serving just couple of hundred customers at maximum; something which will hardly make any difference to 37s bottom line with 3 million customers.

My question as in my original post are:

1. Is it legal? If not, I am not going forward.

2. Is it possible that 37s gets offended? (esp. when I offer comparison with their products)