I would rally-x my car with OEM suspension all day with no worries if I had the chance.
Lowered, it would be harsh.
it all depends on the location of the rally-x. I've been to some where it tends to get rutted and the cars start digging out rocks that could do some damage. but some of the lots are quite firm, and they would not damage anything.
look up "SCCA rally-x" on youtube. you'll get an idea of the couses.
Also, it is 100% legal and 99.99% safe.
May 2014 ROTM
for auto-x: '04 Liquid Grey ZX3
for street: '02 Infrared SVT