Theory EV/SD hours to double:

[doublesnapper]

I currently play 10-20 online or 2 tables of 5-10 simultaneously. I'm trying to guess at my "Hours to Double" my poker bankroll of currently ~6K. My "guess" is at 4.5 BB per hour (playing 2 tables of 5-10 simult., i.e.: $45 per hour).
I read somewhere that EV and SD for a good solid player is 1.5 BB and 12.5 BB at a brick and mortar, so I'm using 1.5 times the speed for online and times 2 because the 2 tables for the EV, but I don't know what to do with the SD figure for 2 tables simultaneously, the only thing I know is that it is LESS than double the SD for 1 table.

My actual figures are higher for the EV and lower for the SD, but I started playing at the micro-limits and many times short handed. That must be the reason, worse players and many more hands per hour.

I would appreciate some advice on calculating my "Hours to Double" figure. Also would appreciate comments on higher limit players' actual EV and SD in bigger games.

One last question: How high is the limit holdem sky?. I.e.: What are the highest games available that still contain "live ones"?. I have no experience of playing other than online.

Thanks in advance.

DoubleSnapper.

Thanks in advance.