Just my opinion, nothing more:
I am not one that usually upgrades software every year. However, this program is so cheap, it makes it much harder to argue not to upgrade.
Whether you are using it for fun (designing personal home as you say) or for profit, you may want to ask yourself how much your time is worth. This is always the bottom line. Anything other than a very simple, run-of-the-mill house can be time-consuming to design. Do you have time to mess around with work-arounds and with trying to diagnose bugs/glitches that may or may not have been addressed with newer versions? Personally, my time is one thing I value very highly. I can't see using TFP software any older than last year's model.
Edit: Then again, you may have to learn new tools & interface when you jump a few versions forward. To each his own, I guess.