My choke point has always been finding another technical-minded parter that gets the industry. Every time I've seen the YC application season roll around, I've thought it'd be a perfect fit for applying to YC, with the connections and clout that come with it. What's stopped me, even at my half-assed pace, was the chance of the huge ego/momentum hit of getting rejected, considering it's still a labor of love (although profitable).
I have a handful of customers that are already paying monthly for "The Vision Lite" at discounted prices: just enough for me to continue development. But larger competitors are sure to move more aggressively into the area over the next year or so, before my current trajectory can deliver on the "this is Star Trek-level shit" experience I've got planned. I'm sure I can grow my customer base at a moderate rate, but I'm not sure I can keep up once the field gets serious against better-funded competitors.
Where do you think the tipping point is between the Basecamp-style "Just get profitable, stay profitable, and move forward" model vs. "Take VC money and turn a two-year schedule into a six months, and get entrenched while you can?" (Fred Brooks notwithstanding)