It sounds like momjrr and the shadow self are handling much higher doses than this, but I would caution others following the thread and making their own decisions on dose to start really low.
I'll probably never take 300µg of ETH-LAD again, if I want to push the dose again, next time I'll go with 225µg. I'm now curious to explore doses in the range of 50-100µg.
I wouldn't say I managed on 750, more like I survived it

450 was stupidly intense on the come up, it was actually very similar to peaking on 750. But once 450 peaked for me it really levelled out, I had a ton of effects but the head was rather clear and everything was just great. Could be a set/setting thing. I haven't tripped for a good while, I'm saving myself for either a good 500 of LSD or another go at 450 on ETH-LAD.