If it's the source I'm thinking of in Spain, 10mg will knock you out into the tryptamine universe so hard that I've actually ordered 4-AcO-MET (which apparently is the same potency but like most 4-AcOs is spread out over a longer duration) and 4-HO-MiPT which is roughly half the potency.
Let's put it this way. Out of all the 4-subs, 4-HO-MET is the most potent and that's even taking into account the fumarate which is going to add additional weight that would not exist if it was HCl (too lazy to do the math maybe someone else will) but 4-subs that are in HCl for are not stable. And definitely not stable as a freebase either. Rapid oxidation in HCL and in the case of 4-AcO-MiPT it was so unstable you would get irritated trying to weigh it because it would absorb the moisture from the air which would result in it actually gaining weight in the milligrams on the scale with the first batch from R*C back in 2004
Luckily that was a high dose material. If you get it from the right place, 4-HO-MET is around the same potency for me than even the most potent phen for me, which was 2C-T-7. And visually... No tryptamine can compare except the 5-MrO-AMT which I would recommend that poison to nobody.
Unlike 2C-T-7 though, there's no physical danger with 4-HO-MET I think it's one of those things that higher doses make it last longer like 2C-C does on the phen side but if you respect it and don't drink alcohol with or mix MXE with it (because of serotonergic properties of MXE) then there is not a damn thing to worry about with doses 15mg and under.
This is also the only 4-sub I heard of a 100mg dose being accidentally taken and the person came out the other side feeling great. So that says something.