Late to the discussion but after 20+ years I have no regrets of choosing the Bronica ETRS system. It can be configured to meet almost anyone's style. Can be light and simple to fully provisioned and most anything in between. Pop on the waist level finder and pull off everything else and it is a lightweight (well, relatively) carry around or add the speed grip and metered prism and you have a camera that is around the weight of a totl 35mm though larger. Add a motor drive and you need not spend money at a gym. The later models though are lighter and better for walking around. Want a camera for vacation but not wanting to blow the budget on 120, pop off the 120 back and pop on the 35N back. Want to do landscape, pop on the 35W back.
Lens are sharp and though there are 3 versions, the original MC, the PE and PEII, the big differenences are only a bit more contrast and the 1/2 stop clicks on the later lens. Look at the inventory of lenses available across the 3 generations and you are well covered incuding several zooms and a shift lens. Extension tubes, a bellows, extenders and something like 5 different finders and the list goes on.
When the line was in production you could feel like akid in a candy store and having a American Express Gold Card was about the only way to satisfy the hunger. Today, the going prices for really good pieces is I think one of the biggest bargains out there. I can put together a basic system for not much more than a Yashica FX3.
As for durability, at least for me I've had no problems what so ever. Any camera can have shutter issues with time but as each lens has its own leaf shutter even if one freezes up all is not lost. The battery is current production, a PX28 so no issue with mercury conversions. The earlier bodies have more metal to being all metal but even the last ETRSi body with the most plastic is a brick in build. A number of companies are supporting repairs and I suspect repairs will not be a problem for many years to come.
If I had a gripe about the system, it is that the company tried to make it all things to all persons and offered such a variety of options and accessories that it could be scary. I have envisioned the committee for development and design sitting in the room and no one agreeing on what it should be so to get the project moving they simply made modules so each committee person was satisfied.
Towards the end of Bronica's life, the system did fail to keep up and was somewhat conservative in improvements. On the other hand, the series was truly universal across the board. Nothing was obsoleted by a newer model. This loss of competitiveness is not as important today as when the series was in production.
In the final analysis I've learned that how a camera feels in the hand and the emotion it creates in the owner is as important and probably more so than the technology under the hood. If these criteria are not met then the desire to photograph does not rise to a passion. As the Bronica can be configured in so many ways, take some time and try different layouts to see if any create that passion.