I have a couple of Hasselblads and use the 45 angle finder exclusively and have for many years. I don't like backwards images and I like the detail that you see with a darkened finder.( no light seeping in). I like the fact that it is faster and easier to focus if you need to do that.
I have a 500 CM and a ELM which is the motor drive. I use the motordrive the most and for the main reason that you can use a 25 foot cable release to release the shutter. Great for shooting kids. While the camera is behind me on the tripod I can move in and move out and tickle or play and jump back and trip the shutter electronically.
I also used to use the 25 foot cable release when I shot weddings. I used the CM hand held with a flash on it and placed the ELM in the balcony and hung the cable release over and down to the floor below. I could shoot hand held in the aisle as well as from above at the same time.
So my recommendation is forget the motor drive for now but get the 45 degree angle finder. The learning curve will be less as it will seem more like your 35mm.