Kubur, the two keris you show are fairly recent creations, one perhaps more artistic than the other (this one was actually discussed on our keris forum at one time). However, i am not aware that there is any tradition in keris culture or in accepted keris pakem that allows for the replacement of the naga form with a centipede. There is no way that the over all form of the keris in any way represents the centipede. It has always been acknowledged as a naga form and there is quite a bit of research and shared knowledge on this to back that up.
But as you have mentioned, there are known pamors such as pamor Kelabang Sayuta which do seem to pay some honour to the centipede. It seems to be a variation on the more established pamor Blarak Ngirid. I don't believe this is a pamor you are likely to find on any older keris however. You are likely only to find it on keris kamardikan.
The centipede does seem to have some folklore attached to it in Indonesia, but again, i am unaware of it being used seriously as a motif in traditional keris culture.