I had two Sundays back in the day.
They’re excellent bikes to ride, especially for cornering and are ideal if you want to ride proper lift assisted downhill. You could use an angle set to slacken the front a bit but its not really necessary.
Maintenance would be the only issue. I never experienced a serious problem like the one mentioned above but bearings are always going to wear out. Whilst you can no longer purchase a bearing set from Ironhorse as they no longer exist, there are plenty available on ebay or from Pearce Cycles. I actually managed to bend a linkage and BETD were able to make me a replacement. The shock is a nightmare to remove, think you have to remove the cranks to get at it.
So in summary, you wont find a better feeling bike to use on proper downhill tracks for that money. However it will be a bit of a ball ache when the inevitable maintenance is required.
If you can increase your budget I’d suggest looking at a YT Tues or the Canyon DH bikes that on sale at the moment, DH bikes take a lot of punishment so I personally prefer a lower end new bike rather than an old top of the range bike.