Those aren't the two mysteries.
I want pics!
Find someone, in your area, that has a Burm and have them help you. Get used to handling a large Burm, before you make the decision to get one. They're not something to be taken lightly...just like any large snake.
I have handled large Boas and Burms in the past, I am well used to it, this is not something I'm taking lightly.
The number one bit of advice I can give you...start hook training, the moment you get the Burm, no matter the size. Repetition is everything. Every single time you get it out of the cage, hook it...I don't care how tame it is/how tame you think it might be. The moment you think "Eh, it's tame enough...I won't bother with the hook" is the moment you end up like me.
I plan to, I never take tameness(?) for granted. (except with my rosy boa..) I have seen many many cases where too much trust is put in the animal and it turns on it's owner.
That happened last June. I still have no feeling in my two middle fingers...not just that they're numb, etc...I have 0% feeling, because of nerve damage. That was from a 12' female normal Retic. All she needed was her water bowl changed. I made the mistake of thinking that it'd be quick, wouldn't hurt to not hook her, etc. She hit me and was back in her cage so fast, I honestly didn't see her. I thought she'd just defensive head butted me, until I saw blood shoot across the room.
Ouch, that's why I never take it for granted.. lol
Make sure you buy from a reptuble breeder. Doesn't matter if you have to spend a few more dollars to do so...its worth it. Don't buy a Burm from someone, if they don't know what it is. "It appears to be half dwarf or het granite", honestly means nothing. If you're not guaranteed what you're getting, plan on ending up with an 18', 200lb snake. Only you can make the right decision, in regards to if you think you're ready for that commitment.
I have spoken with many owners, and have learned everything I could about these beautiful snakes over the past years. The "half dwarf/het granite" assumption does not impact my decision in this case.