I have been using Kontakt 1.2 for some time and am thinking it is time to upgrade it, but don't know which way to go and wondered if anyone can give me some advice. I use the Kontakt Silver player with Sibelius 3 as well, and have a number of Gigastudio libraries which I can import into Kontakt 1.2. I also have now bought EWQL Symphonic Choirs. Basically I want to use more instruments than you can with Sibelius Kontakt - ie a full orchestra instead of 8 instruments, and would like some solo strings - especially a 'cello. I would also like a recorder and harpsichord if it is possible. The budget is about $150. I am thinking Sibelius Gold player, Kontakt 2 (which I don't believe has solo strings) or GPO.
Just some thoughts: I own Kontakt 2, Sibelius Kontakt Gold and GPO. If your decision is between the latter, I would suggest GPO because you can get 1000x more good quality music out of it than from Kontakt Gold. GPO also has a dramatically better sound quality, the samples are vastly superior, there are more articulations and it is a lot cheaper.
Now for Kontakt 2: I saved up a long time and got the "Komplete 2" package a long time ago and recently upgraded to "Komplete 3". I would not want to miss Kontakt 2, because it is a real improvement over Kontakt 1.2/1.5. Owning Kontakt 2 also allows you to have better DFD, a better audio engine, access to those wonderful K2-scripts, has otpimized CPU and RAM usage (which means I can use many more instruments on my old fart of a PC than with K1.5), and, and and. I also love the other bundled NI-software.
To make a long story short: If you can afford it, I would buy GPO AND Kontakt 2. You should also research the option of a later upgrade to Komplete 3/4 (once you own a few NI products, you become eligible for a very affordable upgrade path). The point it that with GPO you get great sounds and with K2 you get a fantastic sample engine which you can use many years to come. Also your Choirs product may benefit from using K", but you might want to confirm that with others.