its almost a copy of the xray active diff. you will run alot lighter fluid in the front then usually. The xray guy run 1000 to 3000 in truggie. There is great right up of it on xrays sight that explains it. but i would still prefere the xray one comes with 2 different bevel plates to tune for high traction or low bumpy or loose traction.. But the losi one looks good with all the lightened outdrives and a great price...
As others have said there is no need for a rear, and I believe you would only use the front or the center, but not both together. My understanding is that if you use the front smart diff you get the most amount of 2wd feel as the front wheels will now be seperate from each other when off throttle. If you use the center smart diff you get a sort of in between 2wd and 4wd feel as there is still some diff drag between the left and right front wheel.
I think the problem for most "e" conversions will be that if you use a smart diff you will only have rear wheel braking.