I found H1000 and Retumbo to be to slow for optimum performance with the 6.5-284. The RL-17 and H4350 produced much lower SD & ES.
RL-17 proved to be faster and more accurate in my rifle as compared to H4350.
Standard disclaimer! Start at a mid range book load and work up, what shoots
Well in my rifle and chamber may be over max for your rifle and chamber.
I settled on:
140gr Berger VLD
215M
Lapua brass
49.2gr RL-17
3077 out of a 31 inch, 8 twist Schneider P5 barrel.
The 6mmbr.com site always has exellent write ups on cartridges pertaining to accuracy, competition.
http://www.6mmbr.com/sixfive284.html