I think the biggest thing discovered here is that the term 'floating thumb' has a 'floating definition'!
For the sake of clarity, when I talk about the FT technique from now on, I will be referring to the 'no anchor/thumb as a muting tool' technique.
Since many other web sites (this one included) define the phrase 'floating thumb' as either;
1) anchoring the thumb on the E-string and lifting (floating) it to play the E-string;
2) anchoring the thumb on the string immediately above the string being played so that the thumb floats from one string anchor to another;
3) the thumb does not anchor on anything, rather it 'floats' with your hand and rests on the strings to act as a mute;
It is highly likely that there are many players out there who refer to that technique using any one of these three definitions and all would be correct.
So if you are going to have a discussion about a 'floating thumb' technique, it is important to know that there are three viable definitions, all of which can be called correct at this time. You may want to clarify right off the bat which definition you are choosing.
--tz