What everyone seems to forgot again, that's what pulls back both Pegasos' and A1's performance is actually not the 1Ghz boundary in the CPU clock, but more the bus speed, what the damn CPU is connected to. Which is only 133Mhz. Even a Pegasos II tops out at 300-450MB/sec at it's memory speed, and ~250MB/sec AGP speed, and this situation is a lot worse on the A1. OK, 7448's 1MB cache can help there, but the bottleneck will be even more extreme for a CPU running at 1.7Ghz. (And let's not count that because of Articia "features" the OS needs to do constant cacheflushes.)

Such a CPU upgrade will be good for nothing, expect to have some impressive results in some synthetic benchmarks. Of course some people would even sell their souls (or all their dancing bananas) to have better benchmarks results on a clocked-to-sky A1 than any average Peg2 board, so such cards still have their potential customers.

As for the Peg2 "1.7Ghz" upgrade, the situation is quite similar, except that IIRC the Marvell chip on the Peg2 could do at least 166Mhz bus speed, so in theory an OF upgrade with different timings (if the other components on the board allow that) could help for a such high-clocked CPU. But this is only a what-if game.