As long as you don't use the high power setting on your radio, you should be OK with the smaller power supply. However, since the surge rating on the power supply is the same as the high power current draw of the radio, you may be able to transmit on high power for short periods of time. Does the Jetstream documentation explain what they mean by the surge rating?
Hopefully, that power supply is protected against overload. If you ever mistakenly transmit on high power with the smaller power supply, you may blow a fuse or trip a circuit breaker in the power supply. The worst case situation would be if the power supply tries to deliver more current than it was designed for and goes out of regulation or damages an internal component. When you overload a power supply, it might deliver less voltage than your radio needs. This could cause your radio to act strangely while transmitting.
If you can afford it, I'd go with the larger power supply now. If you ever want to use the radio at high power, you'll need the larger power supply. You might be able to sell the smaller power supply later to help fund the larger power supply, but you won't get what you paid for it.