Hummingbird flashers have their issues. One post in this area asks a question specifically about them. I tried to detail the best that I could about the issues. More often than not, they tend to have issues reading the teardrop or jig. The smaller the bait, the bigger the issue. Yes, I could get one to work but it was always a frustration to constantly be moving it around.
I've owned Humminbird, Vexilar, and Marcum as dedicated flashers. I have zero issues with either the Vexilar or the marcum units. If I had to pick one over the other, it would be the Vexilar simply because they are a little more crisp in my opinion. We are however comparing similar priced and tricked out models.
Depending on the depther to which you are fishing, the FL8 is a great rig that gives people many years of usage. I've used the 8, the 12, the 18, and the 20. My current go to rig is the Genz fl12. Great unit, runs all day, zero interference from other units, and I can see the smallest of jigs. I fish in waters from zero to 50 feet. My dad uses a Marcum (I think it has the number 3 in it) and that unit is also a great little unit. Works well for what we do.
That being said, many people are going to the actual sonar units. For me, they are harder to read (just what I am used to) and I have had a hard time seeing a jig in sonar mode. If you have a smaller Lowrance HDS5 or 7 you can purchase an "ice Pack" that comes with an ice transducer, mounting case, and battery setup. This will allow you to utilize a unit you already have. I'm not familiar with other models but I do know that lowrance can be set in "flasher" mode. Currently, this is what my buddy uses. We like the HDS 5 because it is small, lightweight, and has all the needed features in flasher mode. Also, we can utilize the GPS software with this unit to pinpoint locations.
The dedicated hummingbird flashers are bulky, heavy, and not really well built. Not to mention the fact that they are louder than a normal unit and the head sensor has a tendancy to break. They do have some nice features on their ice 35 that are not available in similar compared models. Such as split zoom, and the ability to change your beam setting from a 9 degree cone to a 19 degree cone. Most units come with a dedicated cone degree however you can buy other transducers if you want. I think that this is the major issue with hummingbird however and the reason why they just don't pickup a jig nearly as well as the other models. Two other fishing partners both purchased 35's after I got mine (was one of the original testers). Both of them replaced the unit with a vexilar or Marcum. In fact, on of them sent his back within a week of owning it simply because of how unreliable it was in seeing a jig.
Hope that helps you out.
I have OCD "Obsessive Crappie Disorder"