Why fix whats not broken. Mechanical hackamores can be just as hateful or not as a bit can. Of course the longer the shank the more the torque the more the pressure. Also what the nose band is made up of and the combination of torque plays a role also. In the hands of a beginner with little to no experience combined with a problematic horse = disaster. If you have been working your horse with such a "brilde" and have had no problems (behavior or physical like rubbing or what have you) and your happy with things and your horse is happy then dont fix whats not broken. A horse has to be trained how to response to any device. If your looking for a milder hackamore you can try the above mentioned by other posters or you can give the Beetlebug hackamore a try. I have used the Beetlehack (often called) with great success and works well with horses that dont need alot of leverage.
"The question is not, can they reason? nor, can they talk? but, can they suffer?" Jeremy Bentham