No it's not unprofessional and we are DIY so what's it matter.! But that said it's not difficult to do anyway so really no reason why not to have it.
The main thing is that the Spindle comes to a Complete stop before the Reverse Command executes. Mach3 provides a way for this using CW & CCW Spindle Delay before turning on the relavant output. It's just a case doing a bit of experimenting with timings to how long it takes for spindle to come to complete stop. . . .See pic:
Attachment 16682
The Latching Circuit I refered to was the E-stop circuit which has nothing to do with the Spindle Reversing. Only affect on Spindle would be to Turn it off in E-stop condition. The controller would be informed of the E-stop so should Stop spindle starting back up automaticly after E-stop and machine is reset. Not until Spindle Start button or M3/4 command is given should the spindle start up again.
Ask away Chris I for one don't get tired of answering if can help. The harder or more difficult the question the better really because it makes me think deeper.
Often the Hard part with helping is not the actual problem but working out what someone with less experience is trying to get across. Many times I read some question and start computing solutions only to realise that they are actually meaning a completely different thing to what came across in the question.