I've never done it but some of you other guys probably have. Perry has talked about it over the years. Looking for some things to consider. Peaked tiles are one problem if not taken care of along with lose tiles.

Adhesive spread rate?

Type of adhesive?

Anything else?

Any pics?

An angle grinder, with a masons disc, to scuff the tiles, and give them some tooth.

Then screed, or skimcoat with Feather Finish, It may take two coats because of shrinkage as it dehydrates. Then it is just a concrete floor.

The glue spread rate is going to be depend on the trowel requirements the adhesive manufacturer has.

Would a bonding agent have to be applied to the tile before the skimcoat? I've always been impressed your floor prep art.

Not if your putting a rough surface on the tiles, which would remove all sealers. I know ARDEX Feather Finish, will stick to it.

Sure it will stick to it, but for how long and what percentage of the tile must you scarify? Thats the question.

Protect your investment, dont go cheap and just demo the dang tile man. Tile is too slippery to adhere to. Be it tile on tile or wood on tile. If you can, float it. I dont care what any school or industry standard says. Its just like gluing to cutback adhesive, which is NOT a permanent forever floor.

And another point I thought of since I have some Kona in me, cost of Perry's floor prep vs just demoing the tile.

It is going to be considerably less to prep the well bonded tiles surface.
If I'm willing to put a my lifetime warranty on it, I know it will be there for awhile.

The tiles are not slick, if you know how to prep them.

If you say so. I wouldn't do it in my house.

Nor would I do it in my house here. Now, if I bought a new house and saw it would work, heck ya, I'll do it in a heartbeat, without hesitation.

We have sucessfully installed engineered hardwood over ceramic tiles many times, and have yet to have a failure. While I personally am not a fan of multiple layers of hardwood, I see no reason to save the labour costs involved in removing and disposing of ceramic, if it is flat and sound.
Our glue of choice is "Purfloor" from Dural, but imagine any urethane based adhesive would work.

The truth is, one cannot know for certain if any floor that has been attached by adhesive is permanent, or a lifetime installation. Adhesives of all kinds, fail occasionally. I recall a floor I did years ago with Bostik's Best. Part of the job required doing a half bath. Bostik's says Best is not effected by moisture. WRONG. This engineered floor got flooded ( toilet leaked ) and the floor could be lifted right off the concrete. I've seen this happen with refer leaks as well. I'm not saying Bostik's is to blame for the failed floor, the plumbing failed. But adhesives have a lifespan, IMO. I've seen wood floors become loose when glued using all the various types of adhesives, even over wood subfloors. The only permanent type of installation is mechanical ( ie: nailing ). So I'd keep that in mind when discussing "lifetime" installations, regardless of the substrate.

Yeah, but Bostik's has to cure first and the warranty for moisture is from below ie; MVE not flooding.

You're missing the point. And that is that adhesives, in general, have a limited life span compared to mechanically fastening wood flooring.

Gee, I really dont want to get into this one, but what the heck; I can duck if ya throw a stick at me Gary.
I understand completely what you are saying about an occasional glue failure due to mis-manufacture, or some other defect in product rather than poor site conditions such as flooding which would cause a flooring failure initially.
Mechanical fasteners by thenselves should hold a lifetime, all things being equal. Last year, in order to compete with the pricing of off-shore cleats and staples, I purchased a couple skids of very low priced fasteners fro a Chinese importer.
Ultimately, these proved to be of such inferior quality that we were having flooring failures due to the fasteners snapping from the flexing of walking on the floor.
I am a first hand testament to this, since my kitchen floor, installed last year, is scheduled to be removed later this year for this and a general failure of the floor itself. (stoopid me, accepting a gift from a manufacturer for testing purposes, lol)

Get ready, here it comes. Shoot, missed you by a half an inch!

That is bizarre! Either those fasteners ( oh yeah, you prefer cleats ) were of such poor quality and/or your floors deflect too much. That's what happens when the trusses are 2' OC and you use 3/4" OSB subflooring Just kidding.

But you see, my point is, IN GENERAL, mechanically fastened floors will stay down longer/better than adhesive only floors. All adhesives have a life span. The older ones, chlorinated solvent adhesives like Franklin 911 and even much older like the asphalt of the 50"s, get brittle over time and lose their bond. It can take many years before failure. So how long have we been using the current crop of urethane adhesives? 15+ yrs. now? In another 15 yrs, we'll know how long they can actually continue to hold the flooring in place through the constant cycles of expansion and contraction. In theory, they should continue to adhere the floors down, especially engineered. But solids? I don't know. I still hold that all solids should be mechanically fastened down.