Do you record live music or something else. If live music, then the next question becomes do you think you'll have access to the SBD much? If so, then perhaps four channels is the way to go. In my own case, the place I record most of the time has a SBD thats in the back and I record at a different location, so the extra channels doesn't really do me much good. That said, the R-44 is rock solid and I wouldn't have any problem at all recommending it for any situation at all.
The SD recorder is a professional piece of gear and, if you decide to go that route, you won't be sorry except if you ever need those extra channels. The SD are fine pieces of gear and exude quality. They're all metal construction will stand up to anything you throw at it.
As recorders, I don't think you could go wrong with either of these, but all things being equal (meaning the extra $$ you'd spend on the SD is not a factor) I'm saying go with the SD on quality alone.
Since it sounds like you won't be using an external preamp, you probably also want to consider the sound of the built in preamps. The SD has fine sounding preamps, but they do have a bit of a flavor to them and alot of people prefer the sound of their outboard preamps more. I'd say that the same is true of the stock preamps in the R44, but you might want to consider an Oade or Busman mod to enhance the sound of the internal pres...those have had quite positive responses. I'm not necessarily saying that the modded R44 sounds better than the 702, but you might want to give them both a listen to see what conclusions you reach since sound is so subjective and personal.
You're aware that the 702T is not the same as the 702, right? The timecode aspect of the SD702T would also be a basic difference between the two units, in addition to the extra channels.