Even if you are trying to beat an incumbent, you probably don't need everything they have. If there is a true unmet need in some audience, then they will be willing to put up with quite a number of missing features because you are solving their problem better than the incumbent.
Or if you're really just trying to test the hypothesis, you can cheat. Proxy all of match.com and just insert your own rankings and logo. Or just sell it honestly as something that helps you find the best people on match.com. If people buy it, then you know you've got something. If not, then you have learned that nobody cares enough for you to go build match.com.