0.6.0 will compare as a higher version than 0.5 (0.5.0 would also compare as a higher version than 0.5). 0.4.0 will compare as a lower version than 0.5.
In general, though, if you want to strongarm RPM into considering something as a higher version while changing version number representations, you can increment (or add) the Epoch field. Epochs are considered as more significant than version numbers, but version numbers can still be used.