I used to describe the SE as a watered down version of the cube but it's actually what's residually left in the water after the cube is watered down. Big difference.
If you want all of the articualations of the solo strings, then you'll have to buy the Solo Strings I extended and/or II depending on your needs. As for a discount, if you have SE extended then you'll qualify for a small discount on the Solo Strings I extended version but that's it. You have to understand that the SE is sampled whole tone and with less velocity layers (in some cases), where as the full collections are sampled half tone. Solo Strings I full version contains 105,000 samples, more or less, and the SE extended only has about 76,000 samples. And remeber, the SE contains the entire orchestra hence, the first sentence in my response. The solo strings you have in SE are maybe only 4 or 5% of the Solo Strings I collection?
As of May 1st, the prices of all the collections were already reduced and most users don't buy straight from the VSL site we buy from 3rd party dealers where you'll probably find a better deal.
Disclaimer: I am just a user like you. I do not represent VSL.