The v5 (and higher) releases are the ones that get around all of the limitations of the v4 (and earlier) versions of the program.There was no way to increase the capacity of the v4 database model to increase the number of people in the database.
The later versions (v5.2 and up) can read your existing v4.2 family files and write out a new file in the later format.You simply need to have the uncompressed (normal) family file on your computer (the v5.2 software cannot read the compressed backup [.rb1] or the transfer files [.rtx] formats).
I have helped many people upgrade their files to the current format.All of the releases from v5.2 through v8.5a use the same family file format (applause for the programmers... ).
The change in the index behavior is something that Leister programmed in because the majority of users had requested the consolidated index.So it has been present since v5.If you want to go to the Z surnames all you have to do is to press the Z key on your keyboard!The index will jump down to the section where the surnames begin with the Z.
You should not do the database transfer using gedcom.Use the ability of the current versions to read the old database file directly and to write out the new file from it.You do this from the startup screen for Easytree by selecting the Upgrade button instead of the Open button.Then simply navigate to the location of your old file (typically C:SierraGen4) and select the family file in question.There will be a suggested name for the new file (which you may change if you wish), then just proceed.