...on how long you intend to keep your car. If you intend to keep it for a couple of years, Nissen should be fine. If, however, you intend to keep your car for longer than that, I'd spring for the extra money. My mechanic put a Nissen rad in his 300E and it seems to be OK. On the the other hand, he says that he has seen a few Nissen come back because they leaked.
1989 300TE "Alice"
1990 300CE "Sam Spade"
1991 300CE "Beowulf" RIP (06.1991 - 10.10.2007)
1998 E320 "Orson"
2002 C320 Wagon "Molly Fox"
Res non semper sunt quae esse videntur
Not in this weather!