Now I know, I want them all..., but I'm married
So I'll buy one each year or so. To start with the SS (vented) this spring. I think...
The BLAST is what I would call a crossover from the speed series towards the power series. It is not as fast and agile as the speed series, and not nearly as powerful as the Power Blast 2-4. Instead it is a very good medium between both. Much faster than the Rev 1 or 1.5, much more power than the Shockwave, not as fast as the Sonic or Shockwave, not as much power as the Power Blast 2-4.
Personally I feel that if you are mainly looking for raw power, the Power Blast 2-4 would be a better choice than the Blast. If you are wanting good solid power that will drag you a bit but not pull your arms from your sockets and still has some really good speed and precision, the Blast would be the choice. If you want raw eye boggling speed, the Sonic or Shockwave. For ultimate precision without that much power and smooth controllable speed, the Rev 1 or 1.5 SLE.
Hope that helps.