Yeah, mine starts dropping out of regulation, when the Ni-MHs have 1.28V on them (no load).. So i guess you're getting the same results. I've also noticed the same low start and slowly climbing current when it was on the lower limit for regulation.
It would seem yours is regulated as well, but obviously set to a lower current. When i first heard, that all of these above a certain power use the same diode and just the efficiency of the crystals is different, i thought that the current is the same as well.
But i think i just had a realization. CNI doesn't really make 125mW models. And sometimes manufacturers have to use a more expensive product to fill the need for a cheaper product, so they just adjust them to meet the requirements of a cheaper product, and sell it as one..
I have a suspicion, that CNI (by request from Nova and some other resellers) uses the >150mW lasers and adjusts them for a lower current to get >125mW lasers. This way Nova has a mid range product to sell, which is good for them, as the 125mW models are the most popular ones.
What this means is, that X-125s are very probably capable of delivering >150mW if only the current was set to the full 650mA. I'm actually pretty sure of it. And this could be a big deal for people willing to mod their laser. All it would take is to adjust the pot on the driver untill the current would reach 650mA.
Of course these are very hard to take appart, and the warranty would be void, so i don't see many people doing this, but i think the X-125 is a laser that could safely be "pot-modded" to >150mW. (and i don't like to use the phrase "pot mod")
When i finally have time to test the X-75 driver, i will know more. Another thing i can safely do is to hook up my 150mW to a PSU and limit the current to 520mA like you measured. Then i'll measure the power, and i wouldn't be surprised if i suddenly had an X-125..
Oh, and powerful greens often mode hop when the current is too low. Since the X-125 are set for a lower current, there is an even higher probability of this happening. Otherwise the behavior is very similiar to mine, so i don't think you have anything to worry about. If it doesn't mode hop at high currents and when it's hot, i think it's good.
Thanks for the info FML! It's quite interesting, to say the least.
EDIT: Oh, and CNI also doesn't make 175mW models (or at least they say so), so it's possible, they are just 150mW, that came out really high and were then set to a slightly higher current (700-730mA maybe)...