Paul I agree the thruster system in this size boat is a nice to have but far from a must. I have heard some folks getting the motors repaired at a starter/alternator shop when required. Other than that it's just replacing the battery's for the system.
Now the keyless ignition has several components that can fail; touch pad, filter box, or computer module all of which are not available. These can be bypassed with a standard key ignition and some wiring changes however if this is going to be used as a daily commuter boat the down time when the keyless fails and switch over may time some time and most shops do not know how to do this.
If you really love the boat and want to prep to swap over the ignition for when it fails go for it otherwise pass so you sleep at night.
1997 2400 SCR
5.7 Vortec / Bravo 2