For European countries there were up to 6 versions available, too much for beginners. Now there is only one version, which should fit all needs, it combines the speed of sd version with the quality of hd/ihd version. Some users reported much better fps than hd/ihd. 🙂
There is also a new file “W2xp World-models Ext-LOD” available, some errors were eliminated, the LOD for included objects is set from 4/5,000 to 12,000 to match the LOD of 18,000 of the new version better. Still the old (original) file is available. If you have problems with the ext-LOD version, switch to the old “W2xp World-models“.
Have fun flying! 🙂