I bought an Enigma bike unseen for somewhere over 3K, a Planet X exocet and a Neil Pryde Alize for similar money, all three fit fine. If the manufacturer has a size calculator letting you enter all the relevant sizes I don't see that its much of a risk. After all you can always change the stem and move the saddle back and forth, its not that hard to get a reasonable fit. Even if you test ride a bike how long are you going to ride it for? Its certainly not going to be for weeks.