The older lever with the wider tabs does not work with the current G200 or G250 poppets. A newer lever with thinner tabs or a G250HP/S600 lever works fine.
If the silicone daphragm is in good shape and is still supple, I see no reason to change it. The current clear diaphragms do not strike me as being any better or worse.
What really does make a performance difference are the older brass orifices - the new (post 1994) plastic orifices are just not in the same league.
And for what it is worth, an R109 will drive nails a lot better than a plastic cased reg like the S600.
If the silicone daphragm is in good shape and is still supple, I see no reason to change it. The current clear diaphragms do not strike me as being any better or worse.
What really does make a performance difference are the older brass orifices - the new (post 1994) plastic orifices are just not in the same league.
And for what it is worth, an R109 will drive nails a lot better than a plastic cased reg like the S600.