Laying floating timber floor

Need a bit of advice here guys. As per a previous post, I FINALLY found some FTF to match some already installed in another room and intend continuing this from the dining room into the lounge room to replace existing carpet. Eventually we will replace the carpet in the entire house but will probably not use the same FTF in other rooms (maybe contrast it slightly).

This is what I've got; 1969 brick veneer house, wood floors. I checked the level yesterday across the bearers and (except for the rear, around the suspended slab bathroom/toilet) is within about 10mm across whole house. All good, HOWEVER, when the previous owner installed the flooring they first put down masonite, so that's obviously raised the level. Despite that floor using a self-locking system he also glued the floor, both joints and to the masonite AND secret nailed it.

So, I won't be able to key the new floor into the old floor and will use an expansion joint to join the 2 floors. I'll have to also use masonite sub-floor through the whole house, unless I want an ugly step somewhere. But I was wondering what peoples' thoughts were on the gluing/nailing? Rather non-standard, but I have to say it provides a very solid floor, not hollow sounding etc. It's been down 14 years and is fine. The floor I will put down is identical but uses T&G instead of the locking system.