Re: questions about S1625
The S1625 and the S1620 are essentially the same, except for that the S1625 came with a built-in D-tuner for the ZR trem. They were ALL made in Japan. If I remember correctly, the first Korean-made Prestige was the S2075FW, which came out in 2005. I know that my S1625 was made in 2004, and I think the S1620 was from 2003, but I don't know that for sure.
If you can find one, I'd pick it up if the price is reasonable. I think they used to sell for the "normal" S Prestige price - Around $1100-1200. I bought mine used last year for $700. Mint!
At any rate, these will be sought after guitars for years to come if Ibanez continues the MIK/WII trend for their S Series. I believe that the 1620, 1625, and 1675 are the only S Series guitars to all be MIJ, WI neck profile, with a ZR trem. Get them while you can, I say!