I ran the course a few months ago, starting at Gowerton and going anti-clockwise... Some of my thoughts included:
It's quite flat, (for me) and there's a fair amount of tarmac too - out of Gowerton is tarmac for a few miles and then there's a big, long section from a couple of miles before Mumbles all the way back to Gowerton via NCN4, (over 10 miles)
Having said it's flat - some of the dune sections especially around Oxwich / Three Cliffs are a pain in the @$$. Gaiters are invaluable and highly recommended unless you want to be emptying sand out of your shoes every 100 yards. The flat beach sections are mainly on hard-packed sand so it really isn't an issue here.
Lots and lots of places to pick up water. I did it solo and unsupported and wasn't without water for more that 6 or 7 miles. There's WC's, shops and taps outside houses / businesses if you keep an eye out.
Unless the organisers a planning a diversion it's closer to 54 miles - it might not sound a lot but an extra 4-5 miles is a long way at the end
It's a nice enough route, some of the sections around Rhossili and Oxwich are stunning. It should be a great event, showcasing the Gower and Wales Coast Path so I hope it goes well.