MillyMoop, I think the Patapum is so similar to the Ergo that everything we've said about Ergo applies to Patapum too. I've not used a Patapum personally, though.
mondaymonday, lexi twist is where you take the straps back over your shoulders, round behind the baby's waist, then twist them over to cross them, then pull them back under the baby's legs and tie at the front. You end up with a cross of straps just over baby's bum that gives a bit of additional support - you can probably see it explained far better on The Babywearer or watch a vid of it on YouTube if you fancy trying it.