I know.. and there is often very little relation between the two. I too would be interested in knowing the half-life of these compounds, but couldn't find any information on it either, so right now the only thing I really have to go on is reports from people who've decided to try it. There's a lot about the fentanyl analogues that sounds highly variable between users, even more so than with a lot of drugs. There seems to be little consistency regarding dosage ranges, reactions & it is often difficult to find out any solid information- if such information exists. I doubt that anyone is in as much of a hurry to do such research as they are to come up with the next lot of compounds.
From the reports I've read, this does sound like one of the more user-friendly of the lot, but long-term, who knows? It's a shame that the only way we know anything about them is through people who are willing to take the significant risk of trying them and then posting about their experience in places like this.
Edit: Then again, and I'm not saying that taking unknown compounds is by any means a great idea, but at least with RCs we are getting honest, unbiased testimonial that has not been in any way filtered or tampered with to show only certain results or outcomes that favour certain results while dismissing or down-playing side-effects like a lot of drugs that get tested by pharmaceutical companies and then prescribed to people based on flawed findings. I'm not one of those anti-big-pharma types but at least with RC reports, people have no reason to bullshit, and at least the people taking them know that they're signing up to trial a compound that hasn't been researched. Better than being prescribed 'Tramadol- the non-narcotic pain-killer' or 'Oxycodone, the non-addictive morphine' by a trusted physician..