There is a couple of threads here about the EDM700 being available in two different sizes. I got mine converted from 2.25" to 3.125".
I have never used the JPI fuel totaliser function but if it works like the others, it sends the current fuel flow and FOB data to your GPS which then displays the calculated LFOB (landing fuel on board). On any nontrivial distance flight this value is the key decisionmaking parameter. Well, apart from the destination airport closing time 
So there is no in-flight interaction with the fuel totaliser instrument.
Most installations of “modern” engine monitors that I have seen were a dreadful bodge, due to their size.
Peter wrote:
There is a couple of threads here about the EDM700 being available in two different sizes.
My panel space issue is primarily a result of having the half-height RHS panel, which currently houses all the engine instruments—none of which need replacing. So either I get an engine monitor with fuel flow or I have to sacrifice one of the features.
My preference would have the function and price of the EDM-730, but in a 3.125" round form factor. Looks like the next best thing is the CGR-30P or the GI-275. I prefer the interface of the EI unit personally. I guess the only question is whether a GI-275 could, for example, take on the function of another instrument in case of failure. It seems not from what I can see.
You just missed out a $800 rebate on the CGR-30-P/C combo package. You could wait until Aero expo and look for good deals.
Engine monitors, like audio panels, are never worth to go cheap and save some money on the device itself. The installation effort is quite involved and can be anywhere from 20-25 hours for a 4 cylinder and possibly 30-35 + for primary. It is always worth to replace old gauges with a primary replacement. Otherwise you are going to add a ton of T fittings, additional hoses all over the panel and firewall to duplicate all your gauges for map, oil pressure etc etc. It really makes no sense. JPI EDM930 or CGR30P/C combo are really the best choices out there. Wait for Oshkosh, sun n fun, aeroexpo or similar discounts and get yourself the cheaper one of the above.
