[Radio Wrangler]

2N4401/2N4403 maintain their Hfe quite well at higher collector currents than most small TO-92 transistors. They are also quite good for low noise amplifiers operating from low impedance microphones etc (low base spreading resistance)

It's likely that your boost converter runs short, high current pulses.

2N2222A might be a possibility.

You may be better looking through the types made by Zetex (once Ferranti, now part of Diodes inc.)

David