I have a few HP-12C's. I use them as an assessor and some quasi-appraisal functions such as amortization of loans and valuing cash flows. The newest one I have is much faster than the 25th anniversary version. It's not because of one having old batteries either, I switched them back and forth and the results were the same. My 25th anniversary edition uses only 1 battery, while the newest one uses 2. So it's not the exact same calculator from the 80's anymore, it's the same layout and functions, but the newest ones are faster, they do IRR's on 20 cycle cash flows instantly.