OLD KING C
"Imho, it's a very foolish thing to try and out-climb a thunderstorm."
Very well said, mate!
You simply cannot out climb them, I've seen some with tops at FL500 on the tropics.
Secondly you put the acft very close to the flight envelope limits if you climb 2,000 or more above the optimum, so any turbulence will put you on a high or slow speed stall. It's a very marginal situation.
Best way to avoid weather: steer away!