IMHO, I'd go with the lowrance (NMEA2000) for a couple of reasons:
1. It's the same cost or cheaper. Northeastmarineelectronics.com has a LMF200 with an EP-10 fuel probe for $119. Bethel-marine.com has the Navman F2100 for $120.95.
2. It's based on a "standard" NMEA200, rather than Navman's propietary language. With NMEA2000, all data from all devices are shared and available to all other NMEA2000 displays and devices.
3. It's expandable unlike the fuel only Navman solution. For example, add a temp probe and attach it to your riser. You could monitor the temp of your riser right on the display so you know what a base temp is and can easily see if you might have a restriction in the cooling system BEFORE the overtemp alarm sounds.
4. If and when you sell the boat, the NMEA2000 backbone will allow the new owner to use and add anything to it that is NMEA2000 such as his own chartplotter, etc.
There is already cool stuff coming out for NMEA200 networks like a fuel fill that has a led display built into it tha shows the percent of fuel in your tank.

I purchased and installed a Navman 3100 display and twin fuel probes in my 288 Vista. I had the F2100 Fuel in my 248 Vista. Now, I have the Lowrance LMF400 and replace my Navman Chartplotter that bit the dust with a new Lowrance Globalmap. All the NMEA200 info can be seen on either the LMF displayor the Chartplotter, or both.
One thing is...which ever you decide, a fuel flow system is about the only thing I've come across in my years of boating that actually pays for itself. I figured that being able to tweek my speed to get my most economical cruise (and I was suprised that what I thought was my best cruise wasn't), the system paid for itself in 6 months. For example, on my 288 Vista, at 3000 -3100 rpms, which is 29-31 mph, I get an economy od about 1.60 - 1.65 mpg. Good, well at 3300 - 3400 rpms, my speed jumps to 32-34 mph and most of the time my economy goes to 1.7- 1.75mpg. If I have to run in the 25 - 28 mph range my economy goes to hell...1.4 - 1.5 mpg.
Sorry for the long-winded reply...[/list]
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Jvalich
http://www.badcock.com'04 FW 288 Vista "Mental Floss"