You're just shooting 50 and 85mm. Think of the conversion, not what says on the lens.
This is not true. You still need to consider actual focal length. Just because there's a crop factor it does not change the actual focal length of the lens. There's a big difference in distortion between 35mm on a crop and 50mm on full frame. The field of view will be similar but the 35mm is still a 35mm, regardless of the size of the sensor behind it.
These two configurations produce _exactly_ the same image (same distance to subject, same shutter speed):
Full frame: 56mm, f/3.2, ISO250
Crop: 35mm, f/2.0, ISO100
The advantage of full frame is you have lower ISO available, faster f-stops available and more field of view available.
The advantage of crop is you use the center part of the image, so you get better bokeh but less blur for a frame filling subject. You also get a longer reach and better edge sharpness. Additionally when using crop lenses, you have lower cost and weight.
Using a big sensor camera has only advantages once you get faster than about f/1.4-f/2 on the current model because faster lenses cannot be made easily. Instead it is easier to increase the sensor size and image circle and use a sharp f/2.8 lens on a medium format camera instead.