I have a rear rad. I do not see any problem working from the top, you just lay on the floor, it's even relaxing, and if the engine is warm, you can work in quite cold temp!
Most stuff are accessible from the top, bottom or each side. All filters are easy to get at from the bottom. On mine the only things that would be easier from the rear would be the belts, which you do not replace very often, and is doable from the top.
I did the muffler, turbo and EGR from the top and side quite easily, and alternator from the top. I think the only way to access the injectors, valves, EGR, fuel rail and many sensors is from the top anyway
On mine, if you badly have to access the rear of the engine, you could just remove the intercooler radiator, 3 bolts, 2 hoses, 2 transmission lines and you just pull it off, quite easy task.
Other than that,the engine gets quite dirty on gravel road or salty road in winter, the fan just pulls everything up. The rad is easy to clean but the engine not so easy and you have to watch not to get water in your electric connections while washing.