Comparing 90-280, 70-200, 100-400mm SL lenses

Currently use M lenses on my SLS-2 (28 cron, 50 cron, 90 Summarit, 135 Apo-Telyt. Looking to up the kit a bit for more wildlife photography (generally wilderness backpacking rather than safaris or birding) and generally like investing in glass that I can keep for a long time and hold value. Ruggedness / durability are preferences, and I also prefer to avoid swapping lenses a lot, so looking at these three options from Leica: 90-280, 70-200, 100-400. I'd get the 2x adapter with the latter two options.

I'm wondering if anyone else has thought through this before and what you ended up doing and any regrets or wisdom, and any experiences with shooting at the longer focal lengths.

Part of me also thinks it'd be more practical and cost effective to just commit to a Canon EOS system (eg 5Div or similar) since there is some great EF glass for wildlife. Interested if there is any experience with considering or using a different system entirely, too.