One of the groups on my HS team was struggling with full ups (the two bases have only ever flown and the flyer never cheered before) so my coach came up with another variation on the cross leg grip. Sometimes you have to do what you have to do...
The backspot starts in the main base spot, the main starts like a front spot, and the secondary base is normal.
The flyer hops in with hands on shoulders of back and secondary and crosses legs left over right.
The main grabs the toe of the right foot from the front, spins, and has to do a quarter turn to get to their spot.
The backspot never loses contact b/c they can reach around and grab right ankle and throw with their left hand.
The secondary doesn't change anything.
I'm not sure why it works better for them, but for whatever reason it does? I don't think you can even tell a difference from the normal cross leg way if you aren't looking for it. I don't know why people have a problem with new grips that make things more solid. Sure, calling a half up a full up b/c you walk in a circle is sketch to me, but the cross leg vs "traditional" full up disagreement makes no sense to me. It's just a more solid way to do the same stunt.
You can kind of see it in this video - both left groups do it but you can see it better with the back group b/c there's an extra person standing in front of the other one.
eta
@Nvdw we learned double ups at NCA camp and I wouldn't say feet were crossed, so I'm not even sure how the crossed feet way works!