Why do you even think of changing your amp reg or any stock reg if it's working.. you like wasting money then please send them to me by PayPal. I'll be glad to take it off your hands. As for which is better. Both gets the job done..but huma reg are less likely to creep. So many fx amp regs that creep and needing to fire 1 to 2 dry shots before shooting. Do a search and you will find many threads of fx amp reg creep. I have replaced my amp reg cause it was creeping 10 bars. I tried restacking washers, cleaning it, lubing it, nothing work. So slap on a huma reg and everything all good now. If yours is working like you claimed then idk why you even thinking of putting on a huma. If it ain't broken. Dont fix it.
 
A creeping regulator is most often caused by imperfections in the sealing surfaces of the valve seat, particularly when new. Sometimes it will cure itself as it breaks in…the softer material will conform slightly to the harder material as it cycles open and closed a few hundred times. I have not repaired an FX AMP regulator but have fixed many others by carefully dressing the surfaces with 400->600->1200->2000 grit wet/dry sandpaper. 



This problem will also develop as the regulator ages. Eventually the soft seat begins to wear out and does not seal as well as it once did.



If you do experience creep symptoms (first shot after sitting idle for an hour is slower or faster than the rest), check the state of tune before yanking out the regulator. A bedrock consistent pressure is nice but it is not a requirement to hold a tight ES. Just as an unregulated PCP will maintain a tight ES over a broad pressure range, so can a regulated PCP when adjusted properly. In most cases, it’s as simple as cranking up the hammer spring tension (HST) until the velocity no longer increases, then back off until it falls to about 97% of that maximum. Let’s say it maxes out at 900fps, back off to 900*0.97 = 873fps. For the best results, make this adjustment with the pellet you intend to use.