I have flown Emirates a few times in first and once in business. 552K is way too many points for business class flights on Emirates. If the goal is simply to fly an A380, I would highly recommend flying Singapore suites. SQ has been by far my favorite experience as far as service. I would choose an SQ A380 flight over EK with the shower any day hands down. Yikes! $3400 in taxes makes BA flights to and from London seem reasonable. Personally, I'd be looking at other options to get to Dubai.
We've been to the Al Maha twice and absolutely enjoyed it. If I had not already been and I had the points, yes I would spend them and still find it worth it. Having been twice, I don't feel the need to return again and am glad I did it before dynamic pricing kicked in for the Al Maha. That said, I could easily see myself doing a couple of nights as a stopover to the Maldives again.