use of 's-', s'mell' or 'grease traps' in tropical climates

That sounds very wrong. In this following case there may have been s-traps in bathrooms but the water in them had dried up from disuse:

Hong Kong Health Secretary Dr. Yeoh Eng-kiong says the SARS-infected visitor had diarrhea and as more people in the complex came down with SARS and also had diarrhea, contaminated feces spread the virus through the apartment's sewage system and then into bathrooms through drains whose seals had dried up.

Look at the Hepworth site and use HepVo traps.

The message from "Doctor Drivel" contains these words:

Mmm, clever. Wonder how long they last. Also I suspect they're vulnerable to damage by people using drain-snakes. Obviously they shouldn't need to in that situation, but you can bet someone somewhere will do it anyway.

They may very well make things easier for my bathroom refit next year.

A long time.

Nope.

Can't account for idiots or members of the uk.d-i-y Lunatic Association (affiliated).

The message from "Doctor Drivel" contains these words:

Hot even as they're pulled back? I'd expect the hook on the end to snag on the floppy bits.

They are very robust.