How should a startup evaluate design?

I appreciate all of your points concerncing the evaluation of design, in the early stages of development or otherwise, but I wonder what are your thoughts on the subject when considering a target audience/customer/end user? Certain people expect certain things straight away and are easily confused by any sort of deviation from the norm, whereas others can jump right in and find their way around a new environment with ease. I would image that to be a very trick balancing act if you are developing something new - are you going to be bold and different and risk alientating more timid or inexperienced users, or do you stay conservative in your design and hope to still stay fresh and trendy?

I always think of the ubiquitous "home" logo on the top left of almost every page you see (I see you up there "Hacker News"). It's always amazing to me how much people freak out if it's not there or doesn't include a clickable link - they will just keep clicking and scratching their head. There is absolutely no reason for it to be there, but it's like it's some irrational, unwritten rule from on high - even smart designers twitch a little if you suggest leaving it out.

It seems to me that the conventions are followed by just about everyone in order to display information in the quickest and least confusing way possible, and the degree of flexibility in design, from the earliest stages and beyond, really relates back to your target audience.