Unfortunately the "NBOMe era" has led to vendors being more comfortable selling powerful opioids; nothing widespread and horrible has happened (yet) as a result of large-scale NBOMe distribution despite the potency, and this is being taken as validation of the sale of microgram-active designer drugs. This, IMO, is a mistake.
Furanyl-fentanyl and the para-fluoro analogue are around and of similar potency to the butyr-fentanyls being discussed above. Metonitazene is also much too active to be sold commercially, but is nonetheless being brought to market. There's also 1-(2-phenethyl)-4-phenyl-4-propionylpiperidine (an analogue of the schedule-1 opioid PEPAP), which is slightly less potent but still realistically too dangerous to be sold over the internet (not even considering the MPTP link, which even though it's probably not an issue I'd still be wary of). None of these drugs sit well with me being widely sold, and I really fear for what will happen within the RC scene in the next year or so.
On the topic of homogenous mixes, it is theoretically possible to produce an active/inert mix devoid of hotspots that is largely consistent, but I'm not sure I'd trust an RC vendor to do so. I'd personally rather work with pure material and liquid measurement, but I'm sure some see it differently.
EDIT: To the above poster, trans-bromadol and C-8813 are different compounds. Somewhat similar, but the names are not synonymous.