Excellent reasoning about purchasing any shoe really, especially online. Without trying on the pair you want, it's hard to make a call of what your best fit may be. Besides finding a mass of information to make a decision on what size and last to get, there's still a risk to take since everyone has different feet. Unfortunately, there are no known retailers, that I know of, that supply Meermin shoes besides Meermin themselves. So unless you're in Spain, there's going to be a risk in making a purchase online if you don't already have a good fitted pair. Ultimately, there is a risk, but for damn fine shoes it's worth it!
Thank you. I just want to make it clear that I'm not directing anything at you. The subject matter got me thinking about the perils of untested shoes, or any handmade item really (the only way completely to eliminate variation is to mass-produce plastic shoes). Recognizing the risk beforehand helps us to deal with issues that arise post-purchase.
I think Meermin explains that they specifically avoid the middleman, except for Japan. So yes, over the Internet is about the only way for anyone not living in Mallorca. In the US, unless you happen to live in/near a big city with stores that carry imported shoes, the only selection you can try out for yourself comes from the blobby twins of AE and Alden.