Likewise, I've noticed those two models but haven't found many reviews yet. They are both pretty new so it may take a while for reviews to filter out.
They both have plus and minus points, think they make an easy solution for using a projector where setup/wiring could be an issue.
The LG has a much lower lumen output which wouldn't be so good for lights on viewing (if you're talking about 80% tv viewing how much light control do you have in your room?), yet at the same time it uses an LED light source so is more suited as a TV replacement in terms of longevity. The LG model also integrates smart tv features which is pretty cool.
The optoma is bigger, offers much higher lumen output and more powerful onboard speakers (although personally I'd be looking at using external speakers). So maybe better during the day, plus arguably looks better?
Have you seen the Elite Screens
Aeon CLR? It's an ambient screen made specifically for ultra short throw projectors. Again it's pretty new out so no reviews that I've seen and may be tricky to source in the UK. Looks like a pretty cool solution though!
Rich