I own both Liquid Edition 6.1 and Studio 9+ which on my system is actually very stable. I do have a multiboot system with 3 ( separate)Windows xp pros though ,so Liquid Edition and Studio are on different Windows Partitions.
As previously stated Edition is very stable but requires a higher spec PC than Studio and can ( initially) look and feel pretty daunting coming from Studio.
If your reason to upgrade is stability and stability only, wait for Studio 10 which is partly based on Edition engine. Uleads Video Studio 8 and 9 are relatively stable but the interface is ... hmmm. OK.. takes some getting used to after Studio . However they have thier own devotees.
Now Edition.. I use both Edition and Studio depending on ( my mood) Seriouly I just do simple edits in Studio and keep the fancy stuff for LE. If you wish to try out Edition feel free to pm me for tutorials software. Edition does not look, does not feel like, and is capable of fantastic end results compared to Studio. Key framing is a feature of edition that sets it a world apart from studio. Like Adobe Premiere etc, you can play with several video / audio tracks but far more crucial is your ability to control many of the effects to do exactly what you want to achieve unique results. This power thoiugh, comes at the expense of a speedy PC and the sttep learning curve to actually Learn Edition . While Studio does transitons ( fades etc ) automatically for you. in Edition you will need to make sure there is enough outgoing material ( and incoming) to make a effective transition. If you do crack edition though, ( as you no doubt can !!)you will certainly have a ( very) warm buzz of achievment because it is capable of very polished results the sort of which you would be hard pressed to achieve with Studio.
For simple edits though , nobody would know which program edited what.
Good luck