A couple of issues have already been addressed. If the subfloor was inadequate, it should have been beefed up prior to setting the Kerdi base. Other than that, it's pretty much installer error. The Kerdi system is pretty much bullet-proof if you follow the instructions. If the base is flexing, it's due to an inadequate subfloor, an improperly set base (no thinset, wrong thinset), if the membrane isn't adhering to the sloped top of the tray again it's installer error (wrong thinset, operator error, etc). Do you know what specific adhesive they used to adhere the membrane to the base, and what specific adhesive they used to adhere the tile to the membrane? Mastic? Thinset? Premixed or powdered? Modified or non-modified? Brand name? I highly recommend calling Schluter's tech line. They're very helpful and if it's a Schluter problem, they're quite willing to fall on the sword and accept responsibility. Even when it's installer error they help out. Mongo

Nope no worries in letting either of them sit. Do consider wetting the deck mud prior to Kerdi, so the dry mud doesn't prematurely suck all the moisture out of your thinset. Spritzing it with water in a spray bottle will work fine. Kerdi is polyethylene, and as such it will suffer from long-term UV exposure. So if there is a window that will allow strong sunlight to hit the Kerdi, it might be wise to put a curtain over the window if your delay will be lengthy. Mongo

I wouldn't even attempt it. How can he only use "the top part of the Kerdi drain"? That's all the Kerdi drain is, IS the top part, and without it, the whole thing is useless. Additionally, if he put that up with unmodified thinset as is demanded by Schluter, there's no way that's going to bond well with the face of the old tile. Reminds me of an old Molly Hatchet song- Flirtin with Disaster

It's me you're thinking of. Four different tile guys could not figure out how to get the glass tile to stick, so I had tear it out and start over. Went with travertine instead. The Kerdi reps and the glass tile rep both confirmed after installation of Kerdi and after purchase of glass tiles that they were not a good combo. It was a very wasteful and irritating part of my build. I even bought samples of the glass tile and made my first tile guy tell me that he would have no problems with the installation before I purchase all of the glass tile. So much for his word. I purchased by glass tiles from Susan Joblan online. The tiles come with a clear paper face. When we went to pull the clear paper off the tiles, more than 50% of the tiles came with it. In other words, the tiles continued to stick to the paper instead of the wall. And this was waiting a full four weeks with the tiles on the wall before the paper was pulled off. Plenty of time to stick. If you decide to attempt the glass tiles over Kerdi, go with a different type of glass tile. Here is a link that might be useful: Glass Tile with Kerdi Post