Spoke with the guys at adsel today and the comments are as follows-
Q - Can it be put over existing acrylic?
A- Yes, it seems to be ok, no problems so far, although as it's not solvent based it will not break down white delaminated sealer
Q - Can an acrylic be applied over it?
A - Not sure, thats on one of my things to do in further trials
hope this helps guys, in my opinion it's great for the conractor as an installer but as a refurbisher I wouldn't get too excited yet as it needs to be tried and tested.
Also it's great for the installer in winter, so would probably work for the refurbisher on block paving in winter if they had never been sealed before, so could generate income for us, all we need to do now is find away of getting sand into wet joints!!!
PS. it's £89 plus VAT
Hope this helps