RPM results with 4 different makes ESC's.
 
Motor: 2208 2600kv 4.7x4.7 prop
Battery: 20Ah Lead Acid (nice consistent power).
 
Results:
 
Hobbywing 80A, (soft medium and high timing),  :  22796  (11.14v)
Dynam 70A (stock settings) 22796  (11.14v) (22.02a)
Noname 25A (default settings): 21865  (11.19v)(20.72A)
Scorpion 60A (default settings) : 22 321 (11.09v) (20.26A)
 
So... Seems like ESC makes BIG difference in performance.. there almost 1000rpm difference with only 0.05. v difference. 0.05v suppose to be only 130 rpm (2600 * 0.05v)

The other observation, the budget Esc and the high cost esc performed exaclty the same...