I keep hearing that the newer version may be slower to do the work. As for version 7, I have not used it. Linux version appear to use OpenJDK instead of the normal Oracle JRE. They have it part of their repositories, but you can find a Windows installer by Google-ing for one.
I have run my Vista laptop version of LO with version 6 update 23. I was told that the JRE goes downhill with speed of use after that. Some say update 21 might be the best one to use, for now. Some like OpenJDK instead of the JRE, while some do not.
LO people are working on converting the codes that need Java to ones that do not need it. Some extension will still require it though. To be honest, would you want your software package to work based upon someone else's software "package" to work? I.E., when they have issues, then you would as well?
Now that OOo no longer is part of Oracle's product line, will Apache continue to use the JRE as part of the package, or will they go LO's route and replace the coding that require it. I believe LO is replacing some of that code with Python based code instead of Java based.