I have both they are both great units. What it comes down to is the 28 is easier to use pretty much put it on auto depth and use it. The 7 has more options and way more settings to play with, a little bit more confusing to use in my opinion. Marcum doesn't work real well in shallow water. If you fish shallower than 8' I run it in open water mode then it works good. With the marcum I use the graph mode and zoom mode both at one time. I like that better than the flasher mode. I wish marcum had a dash or line to show where the bottom is because when fish come in right on the bottom sometimes it's hard to see that they are there. Also the 28 is a lot nicer for hole hopping 7 is a little big and clumsy. You really can't go wrong with either one just depends on what kind of fishing you do.