I did one once (to a Weber) and regretted it ever after. Reliability wasn't the issue, in that regard the Weber was fine, but it lost a lot in terms of response and driveability.

The injection is very simple by todays standards. In my experience, problems are most often caused by bad wiring connections or dirty contacts in the throttle position switch. Less common are faulty trigger contacts or MAP sensor. The control unit almost never goes bad.