25x-NBOMe are active orally,however it takes a higher dose to get to the same level as intranasal or sublingual. It's an original theory that has at this point pretty much been disproved.
Also I voted for 1500ug+. The dose for 25C-NBOMe is in my belief actually higher than 25I-NBOMe. Threshold may be quicker reached with 25c but the true psychedelic effects take about 1200 ug to really take hold, whereas 1000ug of 25i will be more psychedelic than 1000ug of 25c. 2000ug of 25c on the other hand is more psychedelic than 2000ug of 25i. THIS IS ALL MY OPINION of course, but interesting nonetheless some figures I have noticed through lots of tests on myself and others.
I believe these compounds to be safe to at least the 4000ug range.