I don't think, without experience with 4-HO-MET and LSD in combination, one can come to much of a conclusion on this one, and I dont know of anyone with such experience.
4-HO-MET can be redosed during an experience, without a noticable reduction in the level of effect it produces (at least for a while), for sure, while that doesn't seem to be as much the case with LSD.
If I was going to do this combo, I'd drop the acid first, and then, at the appropriate point in the trip, cautiously snort small bumps of the 4-HO-MET. Insufflated 4-HO-MET takes about 15 mins to get you to just about the peak, and is about 50% stronger on a weight basis (though shorter acting). I've recently been experimenting with that ROA, and am very happy with it for 4-HO-MET.
So like, i'd measure out 12-15mg pile of 4-HO-MET before hand, and then sniff little bumps of 3-5mg at around T+2:00 allowing 15 minutes or so between bumps
One thing i would NOT do is assume that there would be cross tolerance, and raise the dose of 4-HO-MET - if it turned out that the cross-tachyphylaxis (i hesitate to call it tolerance, because we're talking about such a short timescale) was not as strong as expected, leading to a stronger experience than expected. Some people have reported that combinations of 4-HO-MET with other psychedelics can result in unexpectedly intense results.
AFAIK 4-HO-MET and LSD is uncharted territory, so be sure to report.
