I have one and it is for sale! Its an alright unit except for the c map cards. They do not offer the detail in the canyons. Other than that you can see it in the daylight, it is fast but aI like nhavionics better and bought a 6100 northstar. I'll let it go in june for a grand with 2cmap cards.
JW
I ran one for the season last year and absolutely loved it. Best feature: It's so easy to figure out the common functions, you will never need to touch the instruction manual (seriously). Chartplotter, radar, and fishfinder functions are all incredibly intuative. Worst feature: the fishfinder puts out 600 watts and with the common P66 transom mount ducer, I couldn't hold bottom beyond 860' or so (it would do much better with a through-hull, no doubt.) If you rig yourself, you'll also appreciate the color-coded wiring and plugs. When you consider the cost, screen size, and functionality, I give it a big overall thumbs-up--just get the through-hull if you want to get depths in the canyons.
What type of power do you have? A nice feature i have been reading about is that they will match right up with Merc smartcraft giving you the guage info on your plotter screen.. I also like the fact that you dont need to buy a sounder box for the unit to have fishfinder abilities. If my boat sells and I have a 27 Judge built, I will either go with Garmin again or look hard at the M121 series and save some cash. (I am a bay/near shore fisherman)
i have installed 8 of these on our new boats at the dealership i work for parttime and find them very easy to operate install and teach to the customer nice feature also is the tide chart (not on raymarine) go with the 4kw radar if your going that route,in fact ive talked my aunt and her boyfriend to upgrade there boat with this system they stay in shore fluke and bass mainly. we've had plenty of problems with the raymarine systems (c80 c120 )and a very hard company to deal with warranty items, price wise m84 is cheaper and im not fond of the new furuno radars done a few of them 3ish not for me, have not done any garmins yet i think i'll be installing a system on a new 35 scarab sport in may.
hope this helps you out