*rocksolid
*lightweight!
*low maintenance
*quiet
*serviceable

none that I can see...

Finally upgraded from a XCR Suntour and it's like night and day. SID just works. I personally have not been able to find the limits of this fork. I mainly use it for XC and street chasing (rough ridin' - no prisoners type policy - ride it like it's hot!) and this fork never ever let me down: it works in the snow, it works in the dust, it works in the rain and whatever you can throw at it. I've run it at lower pressure than recommended and it feels like the road is made of rubber. I'm now running it at a slightly higher than recommended pressure just because I enjoy racing it. Thing is you have to take a while and feel for your most comfortable pressure. The fork is definitely highly customizable that way and behaves according to your expectations: a no thrill fork and one of the seminal ones at that!
The SID I got came used but it works as advertised. The weight saving compared to my previous 2012 XCR is massive. I'm now regularly accelerating on climbs, SID doesn't hold me back like the XCR did. Frankly speaking, SID is overkill for me but when it comes to forks, that's a great thing, right? It only means I can get better (without risking breaking my neck ;) ).
For the price I got it for, couldn't have found a better fork! As far as I am concerned, SID is _the_ standard and anything less won't do it.
If you can afford one, get it! It's just that perfectly balanced...