I'd be really worried about compressing hydroxy gas, as they'll be in the [i]perfectly[i/] stoichiometric mixture; at that kind of pressure, you could expect a blast of some magnitude. With a large tank and 10k psi, I'd say probably a crater a quarter-mile across.
Also, since hydrogen is so light it leaks through pretty quickly; at that kind of pressure the hydrogen will literally seep through the walls of the container.