Jeffrey,

That 150MHz is the transition frequency, which is basically the frequency at which the gain has dropped to 1. But that's not really relevant in this case.

What I was talking about is the delay in switching off when the transistor comes out of saturation. This means that it will keep conducting for some time after the base current has been removed. For these types you can expect a delay of several µs, depending on how 'hard' you drive them.

Failing the aid of a 'scope, you can try to get your hand on a real switching transistor, like the (pin compatible) BSR16 and see if that makes an improvement.

Good luck,
Rob.