The guru I am hoping reads this would have heard both and would also be able to comment on how each would sound compared to the C-JI doubt you'll find such a guru; but, here's my 2 cents: I have no experience with the Hafler or DNA - upgraded or stock, but I do have a pair of B&K Mono blocks that I had John upgrade. I fretted over whether to spend the $ for the upgrade or not, and tried many more expensive (but used) amps before doing it. In the end I decided to go, and I still use (and love) those amps.
Recognize though that when you pay for the upgrade it's like buying a new amp, and when you go to sell it you will get only a fraction of what you have into it. I haven't seen any Hafler 9500's with Hillig's upgrades sell, but have seen 500's sell for only a little more than stock versions. OTOH, I've seen upgraded DNA 1's which definitely sell for much more than the stock versions. This would be a consideration for me.
I also see/read a lot more about the DNA-1 in the context of great amps, and have never seen a similar regard for any Haflers.
Finally - if I were you (FWIW) I would be inclined to just a/b the stock 9500 with the stock DNA-1. Which ever one win's the shoot out is the one I would go with. I would also keep a close eye on the classifieds for an upgraded DNA-1 and maybe buy one used and try it. This way if I wasn't completely happy I could flip it for little.no loss $.