I would prefer to use a grab rather than 44 b+k on people after knockdowns. A common thing I do is 66b, 66 b+k, 236 K, 66 b+g or a+g, not as risky as the UB and put you in a better situation imo.
This is great against chars like seigfried, but in order to really land the double hit version, you cant really hold the charge. I've managed to hit the 64 damage version consistently, even while holding the charge a bit.