I've had the M260 in three boats I've owned and sold now. It's a wonderful transducer because if you have the right hull configuration (no wood/foam in the boat bottom) you get a clear crisp picture at 30 knts down to 250 - 300 M
I just installed another M260 in my newest boat (24 foot 20 degree deadrise) and next to it, got the palms all sweaty drilling a hole for a CHIRP transducer
Next to the M260 I installed a B175 HWF Chirp transducer (high-freq, "wide")
The "wide" has a 25 degree beam which complements the M260 (which has a narrower beam)
With the M260 you get targets both shallow and deep at speed. With the B175W, you get the 25 degree beam which is excellent for tracking your gear---it will clearly show a cut-plug spinning at 50M
The small black transducer is a P79----it's an in-hull that operates in extremely shallow water (something the CHIRP transducer does not like to do, especially if the freq. is tuned too high)
I've had the Airmar SS260's (I had a pair of them in my last boat) ---it was a very expensive install---the LF was good for tracking gear but the HF was a waste of money---didn't provide much more target clarity then you would expect from a
$ 100 P66 skimmer stuck to your transom.
Instead of dumping more 1KW transducers in my newest boat, I have a P66 to complement the 1Kw big boys. That P66 is an excellent transducer---a guy who knows the settings on his 50/200 600W rig can easily glean about 80% of what you'd get from the more expensive CHIRPS.
But it's really impressive to see the clean crisp target separation on a CHIRP, something you don't necessarily always get on a 600W unit
I DO NOT mix transducers on the same head set (with a splitter or a "Y" cable or an Airmar junction box) I have a separate MFD for each transducer--that way, no screwing up with the wrong setting or the incorrect wattageoutput