A gapless audio engine has nothing to do with a programs stability. While it would be nice to monitor without hearing the slightest gap, it still doesn't effect the outcome. which is perfectly aligned audio.
It seems like you're having problems in X3e, moving to the current version wont help your stability any.
X3e & Platinum are probably the most stable versions of Sonar ever released. I don't know what it is but saying you can't see what it could be because you have a beefy system doesn't mean it isn't so.
Really we don't know enough about your system to come to any conclusions. Sadly though you've come to a conclusion about Sonar based solely on your system. I would think if your livelihood depends on it that you would get it sorted. I know I would have had it sorted or moved on a long time ago. Lets face it, most DAWs can do pretty much the basics and comping is one of those things.
I would work now to get it sorted once and for all or know definitely that I need to move to another DAW.
Just as an example, in recent times its been uncovered that just having Asio4All on your system can be enough to cause instabilities that have long been blamed on Sonar. Delete Asio4all and everything is fine.
Another one. HD Audio drivers for on board sound devices are being found to be the culprits behind audio problems and disabling them has fixed issues.
For some setups, not using HDMI connections with a monitor screen for audio has fixed some peoples problems.
There are so many interdependencies that go to make a stable system that in some cases it will take some effort to create that perfect setup. For some of us it works straight out of the box but not for others.
Now lets see if we can't help you sort this out.