Depends up on which model and which installation shop you choose.. Usually aftermarket moonroof do have some problem(s).. Not much about water leak.. instead.. noise produce from the aftermarket moonroof.. My car.. I am kind of little disappointed about choose 10th anniversary with aftermarket sunroof , (couldn't find nice EX in Korea..) and I have Korean Brand aftermarket sunroof with no problem.. Mine is powered out-sliding.. Anyway... I am saving money toward getting moonroof that I am going to explain at below..

If you really want aftermarket moonroof .. I recommnad "WEBESTRO HOLLANDIA INNER SLIDING STRATOS-700 (43.5)".

Trust me nothing else. Other cheap brand will have problems..

Price: In Korea.: US$1,000.00

Here is some info about the company..
Maker of OEM Moonroof / Sunroof of following auto manufactures.
<Germany> BENZ, BMW, PORCHE, VW, AUDI, OPEL, FORD, <USA> GM, FORD, CHRYSLER, <France> RENALT, PEUGEOT, <Italy> FIAT, <Japan> TOYOTA, NISSAN, <Korea> Hyundai, Kia, SSyangYong..

Made in Holland..

http://www.webasto.com/index_en.html

I hope this helps..