The main advantage to the electric control type options are having the third function at your fingertips as you work the loader control.
While we are discussing third function as opposed to diverter valve a TRUE third function would be an extra spool valve. A TRUE third function would be like what comes on a loader with a 4 in 1 bucket. Many of those have the third spool that is operated by twisting the loader handle clockwise or counter clockwise to operate the third function.
Anything else with electric is a form of a diverter valve. To have all three functions at the front would also be dependent on your hydraulics having the capacity to operate three functions at once and then you have to develop the coordination to operate three movements simultaneously. I haven't looked at the WR Long kit specifics beyond it's price so I can't say I know what it does different unless it pulls hydraulics from the power beyond rather than split and existing function.
My selective control valve (SCV) actually came from the factory with an unused spool. I decided it would be easier to build the solenoid selector valve (diverter valve) than to hook that up. It's original intention was to be available for a rear remote and I may use it for that one day. Some selective control valves are stack-able and you can add sections if there is room.
Some have tied into an existing rear remote for a third function. In my opinion that would be a botched up approach that leaves you reaching for a separate control to operate. Might as well not have a third function if you have to take your hand off the loader control to operate it.
The most common diverter valve is the
DSV-62-08-12. As LD1 stated all other connections will be machine dependent.
I too mounted my valve where the original input hoses could connect but after that everything you need will be extra.
Hopefully someone with your exact or similar model will have developed a solution and list their fittings and all to save you some hassle. That is what I did in the thread I posted to my setup. It may help someone with a tractor like mine some day.