No, I didn't caution against it ... I cautioned about not wiring as close to the drain as I had done.
Just be very sure your cable is rated for use in showers by the manufacturer.

Ok...thanks very much. As you can see in my photo of the cables in the shower, I left plenty of clearance.

I hope your cables are not on the same spacing as in the shower for the rest of your floor. Most cables are on spacings of 1-1/2" to 3" depending on the application. Yours look quite wide.

You have 2 cable sections that appear to be less than 2" from the Kerdi flange. That's too close.

On the rest of the floor the cables are spaced as per man. instructions at 3" using their guides...I will post up another set of photos later. What is the concern with the cable being less than 2" from the flange?

There's quite a bit of heat generated by the cable and the potential to damage the ABS drain flange is possible. What is True Heat's clearance spec to walls, fixtures etc.?

The directions say 1" from walls and 2" from fixtures, 6" from drains...I took that to be drain openings but perhaps I'm wrong.

I would be concerned with the Schluter drain due to the thin ABS flange. Any ABS plumbing fitting or pipe is much thicker and can take more heat before distortion.

The main reason for 6" clearance on drains has to due with toilet flanges. If the wires are too close it actually melts the wax seal.

Your heated shower floor is not a normal everyday occurrence, so I doubt anyone can tell for sure whether this will be a problem. To me it would be better to error on the safe side. It's not like you can't move the wires. Or is it too late?

I'm afraid it is too late...I have already applied a coat of mortar over top. I guess I will cross my fingers and hope for the best.
By the way, thanks for the referral to Tile Master in Barrie...very helpful and the Schluter products are priced a whole lot better than at HD!

I'm curious, is there anything in the electrical code/plumbing code regarding placement of electical heating within a shower floor? Or, is this left to the individual area/municipality/manufacturer?