I have tried both several times and although i would say i notice a slight difference (I prefer lsd-25), I know several people that look at 1p-lsd as a prodrug (as in less side effects in higher doses). If you have trouble getting lsd-25 from a trusted source i would recommend 1p-lsd for sure. They are 99% the same in my experience.
The highest I have gone is 400 micrograms, like I said I can't tell them apart!