Umm I think your "facts" are off a little bit buddy. Thebain is an inactive alkaloid and is actually very toxic in high doses. Many believe it has no agonistic properties at all. The reason why many pharmaceuticals are derived from thebaine is basically to limit homebrewers i.e limit competition. You see , at that time in the early 1900s the market was saturated with Heroin and Morphine, very easy to manufacturer no money was being made. So to eliminate competition a team of German scientists manufactured a few semi synthetics and you bet your ass they came with PATENTS. Cha ching.... Monopoly time. All they needed to do now was criminalize morphine and heroin. Which they did shortly after. And that''s how you win an opium war LOL. Nah, but it's really fucked up.
As for Methadone, No, it is not synthesized from morphine. It's just synthesized. It's 100 percent synthetic, made from the ground up in a laboratory. Unlike it's semi-synthetic counterparts, No opium alkaloids are needed to make it.
Another thing, the effects of opiates/opioids are completely subjective. It really depends on the user. So to say that one opiate is exclusively "energetic" whilst another is exclusively "pain killing" is completely redundant.
Just my 2.