I do think nitro rules on grass for run time. I have never tried Lipo but on grass there is no way I have been able to match run time. All so on my nitro if I want more run time I just put in a bigger fuel tank and most of my nitro get WELL over 20 minutes depending how I drive. All so IMO electric just does not have any sole. I was thinking about taking an electric and putting in a sound system to make it where there was a motor noise. But I do agree they are all good and it has to do with personal preference.
The whole sound thing is debateable, personally you cant make a sleeper nitro truck though, where as the quietness of the electric allows you to throw in a low turn brushless system and a nice li-po, where the competitor would never know what your packing...of course until they challenge you in a race.
True you can put in a bigger fuel tank, but theres only so much room for that, where as we can just add a high capacity cell. I also read someone talking about that cost of batteries, even one $50 battery is less then the cost of two gallons of nitro fuel, so your looking at around 200 good hours of use on that battery pack, dont think I could say the same with two gallons of nitro fuel. Also consider unlike nitro fuel, there are cheaper alternatives from batteries, starting around $20 and up, but as with ANYTHING in this hobby, you get what you pay for.