Babies can be worn legs out from birth as long as they're properly supported from knee to knee with the knees higher than the butt. I've always worn DS legs out because it's how he preferred it. With the Moby hug hold, you don't have to put a panel over his head if he's leaning against you or had any head control. Sounds like he doesn't like his legs being constricted, so try the hug hold legs out and see if that helps.
And not even my son seemed to love BWing those early days. I just wore him anyways because I had to get stuff done. As long as I stayed on the move and was calm, he would calm down too. These days he LOVES being worn and will even ask for it.
I used the Moby first and then quickly added a mei tai to my stash. It was less frustrating for me. I was getting angry at the Moby which in turn made DS upset.
MTC BASIC - No Frills Solid Color Mei Tai Carrier :: Meitaicarrier.Com LLC Online Shop
That lady who makes MTC is well known for quality mei tais. For $30 it's a great deal!
I also really like ring slings for babies.
sleeping baby productions | product detail
I LOVE my SBP ring sling. This one is a good one to start off with and it's reasonably priced too!