Hi Roger,About 50% of what I have been shooting has been my grandkids sports ... etc.
ANY IDEAS ???
I'm not sure if my contribution will help, but maybe the empathising will.
Due to circumstances, I'm stuck with equipment that's 10 years old, bar a few Zeiss ZF lenses.
When it comes to long lenses, I have wondered whether to stay with DSLR or go mirrorless. Please bear in mind I'm stuck with a D2Xs and a D300S (!!, yes, I know), so presumably any of the mirrorless cameras with FTZ adapter will perform (much) better. In the final(ish) analysis, I decided that I would be better off (for the wildlife work I do) with a D500 for the 300mm and 600mm, and a mirrorless Full Frame (FF) for my manual lenses, (mainly for the ability to confirm manual focus via the EVF focus thingy, as well as the other advantages over the aged DSLR system I have). However, I like to go around in circles, backwards and forwards, and take procastrination to levels that make emerging mountain ranges look quite nippy in comparison.
The one thing that makes me doubt my final(ish) analysis is Sony with their 400mm and 600mm offerings (I'm sure a 200mm and 300mm will pop up some time). Both available, lighter than the Nikon equivalents (by some margin in my case as I have the heavier first VR version of the 600), and on balance, better image quality (including with extenders). These three (four) attributes are the top three (four) in my book for any fast long lens. Combined with the better AF features of the more recent Sony mirrorless cameras, I find myself 'umming' and 'ahhring'.
I sold my Nikon 200mm f2 (hardly used it) for a good price and have considered selling both my current lenses to fund a Sony camera/long lens combo. While, this is the only viable alternative to my Nikon set-up, I have some nagging doubts as to the poorer ergonomics, poorer menu layout, and possibly lesser build quality of the Sony cameras. It would eliminate the need to buy both a DSLR (offsetting a little the resell loss on the Nikon lenses) and a mirrorless FF for my current (easily adaptable) lenses. However (there are a lot of 'howevers'), what if Nikon bought out long lenses, presumably (from a marketing point of view) at the same time as the Z9, and they are the equivalent or better than Sony's offering. ...or it could be a couple more years before the lenses are out. Presumably they will be of a new design as all Z lenses have been so far, to take advantage of the larger mount. They'll have to be better, won't they?
...and if the Z9 (or other Z cameras, with updates) can run a Z 300mm and 600mm better than a D500 (D5/6) can run a F 300mm and 600mm, then maybe...
...but then I'd have to wait a little while for the production Z9 to have any bugs shaken out of it...
...or mabe a Z7II or Z6II with updates will suffice?...
...or maybe Sony will come out with a body that has improved ergonomics and a more logical menu system and...
As you can see I'm getting indecisive where before I was quite decisive (maybe). I'm guessing this is your problem too.
As it is, I'm sitting on my bum and will wait to see what Nikon throws out. I'm fairly lucky in that second-hand prices are better over in Europe than in the US, so I'm able to sell on the long lenses for around 50-75% of their current new value if I decide to go Nikon Z or Sony. High value lenses always fair better than low value.
The cameras themselves are essentially 'disposable' items, in that once new and 'better' models come out, their predecessor's resell value plummets, as you know. I'd be reluctant to buy a £/$6,000 camera if a more future-proof camera came out soon after.
What throws all this around and makes a mess is that reality kicks in quite often and I find myself asking, will I get a real-world improvement in my images if I make the switch? Will I obtain images on a new system I won't get with the mature system I have now? When will my current system start to fail (electronics fail, ...a lot. My D300 is playing up a little, and the AF motor needed replacing on two lenses), and won't that mean an investment in a new system anyway? When will that cross-over happen and can I predict it and make the change before it happens?
...erf. Back to square one.