As one of the non-garaged, I asked Tesla directly about this prior to ordering, and was welcomed with open arms to use SCs as my primary source. I've done just that for 8 months and have no plans to stop. My next garaged dwelling will be in a country that ironically just committed to national EV readiness - however, no sign of Tesla there, and the effort is being underwritten in large measure by the Chinese. Anyway, I used to wait in line at the Costco for gas. Now I make a few calls or catnap while supercharging every week or so. Once any range anxiety subsides, you'll find that charging weekly is just fine unless you drive a lot. I met one fellow recently who has over 90,000 miles driven. He SCs daily to get home, *and* has solar for a full charge in the morning. Pay NO attention to the Handwringing Busybody Contingent that would dissuade you from your purchase. Trust, but verify - get it in writing. And enjoy your pending Model S - it'll be the best *driving* experience there is. The rest, well, time will tell.
Caveats:
I live in an area in which Tesla committed to DENSITY as well as distance shortly after I was told it would be fine to use SCs. Your area may vary, and the rate at which SCs are opening has... not increased.
Also, given the sophomoric ambiguity in one of the latest examples of poor communication from Tesla (the now-infamous Letter), were I you, I would not only call to ask the same question I did, but to require the clear answer thereto in writing before committing to your order.
I would not and will not buy another Tesla without that promise being reaffirmed in writing prior to purchase. Unfortunately, by not clarifying the letter, Tesla now has an emerging credibility problem. At best, either they're still deciding what to do and when, or there is a disconnect. As an owner, I'm not happy about that. As an investor, I will take this into account during the next periodic adjustment of my portfolio. While I would prefer to continue to own both product and equity, this may turn into one of those situations where it will be one or the other or neither.