I partially disagree with "...developers don't have access to all of the hardware that is out there...". 99% of the boards are based on the same STM32F series (105 or 446). The POG version has been sold (manufactured) in thousands of units. N3XCC's green & red boards are an improvement of the SQ6POG's concept, are of superior quality and I have two of them in use (check the footer on RB website). The latest boards from BI7JTA are a rip off (*cough* decent clones?!) of the N3XCC red board.
Now, with Arduino and STM32F105 hitting the wall, the problem will be sourcing a quality (>180 MHz) board, especially if you live in EU. Scott's boards are great but they don't come cheap, not to mention the customs fees and transit time. BI7JTA's are 30% cheaper but again I would like to know a shop within the EU for a decent and affordable board.