Just peeping in ive done this combo, albeit at a little higher dosed (1000ug of each if i remember right). No nBOME specific tolerance at the time but had tripped a bit up until that point and most likely around the time of this trip. I dont know how much that plays a role in your question but I dont remember because it was a while ago. BUT
i can say this is one of the few times in my trips that I was overwhelmed a little bit as well as made very uncomfortable by the vasoconsticiton which was as severe as I had ever felt from any nBOME. I had taken the two on a solo bike-ride through some of the southern Californian canyons as I had done with each individually (meaning 1000ug of one or the other on seperate occasions). This time though, it was just too intensely visual and when I stopped to take a break from biking I would feel a creeping (but very noticeable and on the verge of painful but not, if that makes any kind of sense) pins and needles just crawl up my leg and it was so incredibly unnerving while tripping that hard I had to end the ride and get home to try and remedy the vasoconstriction thinking that getting home and smoking weed to vasodialate and soak my legs in warm water would help and it did a lot, but the whole trip was essentially ruined by my worries over my legs and it all just equaled up to be an anxious time.
Also, heres a lil slightly related report of an instance with me and 2 of my friends
http://www.bluelight.org/vb/threads/679079-25B-NBOMe-warning-bad-trip-non-fatal-overdose-1000ug
...given it was 25b not I or C, but the nBOME series more and more shows something....off. They just are a step too far in my personal opinion. Ive had great times on them dont get me wrong, and to be honest its sad that that the good things from these drugs are accompanied by so many haphazard risks because they do have some wonderful visuals and at times, great insight and clarity...They just are a step too far in my personal opinion though. When there are other RC's like 2cs or as mentioned above DOX's, nBOMES are really just, well dirt.
Honestly too, even the fact that Ive mentioned this included with the fact that youre already aware of some of the physical risks, youll probably end up having thoughts about your body the whole time and have to constantly be consciously doing doubles-over to make sure you ok, even if the drug isnt actually doing anything. (even though it could, that's the russian-roullette-ness of nBOME) What im saying tough is that you may have an anxious trip. Maybe Im wrong, IDK, id just thought id share my experience with nBOMEs. Fun drugs when dosed right....but what the right dose is? Now that is something that varies so sporadically from person to person, and on top of that changes from one time to another; that ive decided I cant be a part of these drugs anymore.
I mean you be you dude, and honestly the dose you mention SHOULD be fine for one of you let alone splitting it. Still though, just think is that risk worth it?