Rivendell Bikes have some advice HERE. That will take you to the first page, look along the right side of the page and you will see three other links under the third topic "Bike Fit". He likes to put people on large frames. Most people would tell me to go with 19", my LBS put me on a 21", and the Rivendell method would have me on a 21-23". My bike fits fine other than I need to raise the handlebars some, so I think that bikes at the low end of Rivendell's range are a good fit, based on a sample of 1! I would say that you should run through the Rivendell method and if it comes out as large or larger than the size you are leaning towards it will help confirm your thinking.

Unless that is the method you have already used, then I would say that it works pretty well and I would not worry if it comes out a size larger than what others recommend.

Ken