I also have downloaded the Windows 10 Technical Preview and I am very impressed with its stability thus far. However, AS EXPECTED, the latest Avast version would not install. Moreover, as far as I know, many of the other top AV solutions are a no-go as well.... and that is also to be expected. However, there are a few lesser-known AV solutions that have been tested (by people at tenforums.com) but I wouldn't touch any of them with a ten-foot pole so I'll stick with Defender until an Avast solution is available.
Also, I would like to add my two cents regarding the Windows 9 comment "being around for quite some time." Specifically, I would like to know where to get the trial version and who is actually using it? In fact, most of the Win 9 information is mostly obtained by "leaks" from Microsoft employees. However, if I missed the trial, and there are many running Win 9, then I apologize for not knowing about the masses. Anyway, I will tell you that (I believe) Windows 10 is actually a Win 8.1.2 clone with some superficial cosmetic changes. My conclusion is based on doing intensive functionality checks, driver installation verifications, and DLL/EXE comparisons. Now, if I am incorrect in that assumption as well, I would like to know (specifically) how anyone determined it was a Win 9 clone.
plsrepli