I'm not sure what you shoot and what lenses you have, as that will play a big part.
I bought 5ds (non r, but they are almost identical). I can tell you that it is insanely demanding on good glass and super steady technique. So much so that your average L zoom just won't resolve much more than mk IV... Sigma ART primes, Canon 70-200mm, 50mm STM and 400mm 5.6L are OK, The rest not entirely. If you can tick those boxes you will be rewarded with tack sharp 50MP image.
Noise is another one. I would say it maxes out at ISO 800 and that's pushing it. No fast fps either and huge file sizes. For general use the mk IV is probably better suited. But if you need the res you need the res.