Having spent a few weeks riding the new loop it's not as bad as I thought it would be.
On the downside:
It's chuffin busy at weekends, not so busy that quick laps are impossible, but busy enough that you'd struggle to get a clean run through any section. Not the end of the world, but it's certainly busier than it used to be.
The swinely facebook page is full of moaners moaning about everything from slower riders, to braking bumps, and 'XC' riders cutting the ques for sections.
On the plus side:
It's weatherproof, the fire roads are suffering (very badly in places) more than the trails when it rains!
While a lot of stuff that ran vaguely nearby to the new stuff is beyond riding (or just not as good as the new bit), there's still loads of off-piste alternatives to keep a sense of variety if you ride the loop regularly.
If it's hugely popular then it might get more investment and more trails. Or cynically it might get overused and eroded.