From a more historical point of view, 1999 was the fourth year of production of the SL1. Even though they had a production Soloist model since the early 90s, they didn´t land on the SL1, RR1, KV1 format until 1996. The SL1 has been exactly the same ever since, even though color choices have varied. To me the Soloist is the archetypical and original neck-thru superstrat, and I´ve had my SL1 in constant rotation since I bought it new in 2000.
The one thing I don´t fancy with the stock SL1 is the Classic Stack singles. I think the Classic Stacks work fine in some other guitars, but there´s something with the general build of a SL1 that doesn´t mesh well with them. I´ve played several SL1s, and it´s the same thing every time.
