agreed. however, imo, the big one that people overlook is the 'network effects' one. just as it would be appealing to be facebook, trying to become the next facebook is darn near impossible because of the network effects.
Getting someone to use your timetracker can be an uphill battle, but unless they're deriving value from other people using the same timetracker, you've got a fighting chance of at least convincing them to give it a try. But if much of the value they get from timetrackerX is that all their friends and clients are also on it, and they share time info around... it's extremely hard to even begin to compete with that, because it's not a feature you can replicate.
Getting someone to use your timetracker can be an uphill battle, but unless they're deriving value from other people using the same timetracker, you've got a fighting chance of at least convincing them to give it a try. But if much of the value they get from timetrackerX is that all their friends and clients are also on it, and they share time info around... it's extremely hard to even begin to compete with that, because it's not a feature you can replicate.