I guess we are going back over the ground a bit here, but with several long threads to plough through that's likely to happen!
If you good people are considering the R-44 - which I love to bits - there's one downside which does affect my use of it, and that's lack of properly mixed monitoring. When recording, you can't vary per channel the level and pan of each of the four into the headphones. Each channel can be heard on its own in mono, or you can hear the first pair in stereo, or the second pair in stereo, or all in mono. You can vary the channel levels on playback - there's a menu screen with four individual faders, though it doesn't work when recording - but again, you can't control pan.
So say you were recording a vocal quartet standing in a line, and you had a mic for each of them, you would not be able to have channel one hard left, channel two slightly left, channel three slightly right, and channel four hard right in the headphones. It would come up as one left, two right, three left, four right, or you'd have to use mono. Or if you want to use a stereo pair plus a spot, the spot will always come up on the left side as there's no way to have stereo on one and two plus channel three on the right (or centre).
So if you need that kind of monitoring, you have to use a separate monitor mixer, which is a pity - and there's currently a surprising lack of suitable small 4-lines-into-two mixers on the market. But if you just want to check that you've got a problem-free sound in each channel, and you don't need a balanced playback till you get home, it's fine.