I have used the 200 and the old 180 models but not the 400. The others have always worked well so I think there stuff is good quality. Not sure how it works with just 3 electrodes. Might be fine. We used 7 positions years ago but now o think it is just 5.
I just did a 48 Hour Holter on our Male last week. With the DR400 it can record up to 14days.
We have had the DR400 now for about 6mo with no issues. We have 4 Dobe owners and a total of 7 Dobes in our group. No one has had issues with the unit. One person did have issues with the electrode pads falling off. I know we just received an email from Alba a few weeks ago. That they had issues with the electrode pads not sticking well and they changed to a different one. But I've had no issues with the ones we purchased with the new DR400. We always shave the area clean area with rubbing alcohol then stick the pads and unit on.
I like it a lot. Very small and you just attach the 3 Electrode pads right to the unit. Plus it takes no batteries or cards.
Plus Alba gave us a great $500 trade in on the DR200 we had for about 5yrs.
Down side of the DR400 is only for Windows not Mac's
Down side of the DR200 is that you will need a larger card if you want to record for multiple days.