You can't really say one way or the other yet. Both laptops are brand new (the m170 not quite as new as the 7800 is the only new part, but who knows, the 7800GTX may cause problems).
Sager does have the tech & feature advantage, not to mention the price advantage.
Dell has crappy tech support, Sager has this forum. NBF was originally setup for them and they are always responding to people.
The m170 does still look kewlier due to the LEDs and personalization shield.
The Sager has the kewl jukebox function without booting laptop.
The Sager has built in TV tuner. (This is a big one to me, I'm still working on routing a cable and RF socket into my iXPS2 case to use with MiniPCI TV Tuner)
I don't like Sager's dead-pixel policy, however Dell's use of only Samsung LCDs for American m170s pisses me off. Not sure if a dead pixel or horrible light leakage is more of annoyance to me.
It's still up in the air until a few months at the earliest after both laptops have been used and we get real world results.