I have no idea how much is released "immediately," but if you crush them up, parachute the powder and just eat the left over "shell," the effects are essentially the same as if I were to take the same amount in IR form. Eating them whole without messing with the pills, I feel the effects are also essentially the same as IR, but more so cheat up on one. A rough guess as to how much is released immidiately, I would say, is around 30-50%, but whether ER or IR formula, always takes about 45 min to feel the effects. And then the rest, the other 70-50%, would probably be released over T+45min+2-4hrs (or from 2 to 4 hrs later). Hope that helps.
Long time lurker. Glad to have finally joined. And the whole first post biz is making me grin.
p.s. Also, I find I really enjoy the ER effects, albeit crushed up and parachuted, more than the same does of IR. Don't know if this is all just me, but friends (okay, only one to be honest) have had the same/similar effects.
