Actually the question is do you need features that are only available in the r100. That would be the best reason to update C2.
As far as I'm concerned, I've kept up with beta version for... almost as long there has been the stable and beta branch.
For some versions, I waited a couple of days to see if no one would report breaking/truly annoying bugs that may occur with the features I was working with in my projects.
Some time it happened, most of the time it didn't.
Some beta versions had a trouble with the exporter, making it impossible to export a final project. That didn't happen while I was in any need to export a project and also, Ashley makes quick work of fixing those bugs and releasing a new beta to correct them.
R100 has been a bit different. It took some time before being released, and it provides the shiny webGL and exporter features.
If you are up for the ride of trying those features, you may want to update right now.
There as already been some bug reported, but as far as I'm concerned, what I've tested so far has worked as expected.
Don't excuse for having worded and worked a post, there's always someone in C2's community to take the time to read it.
It's part of the game maker toolset to be able to cope with long and written topics.
Also, the question is legitimate.
At worst, even if it isn't advised, you could install a second instance of C2 on the same computer without uninstalling the previous version.
Another thing that can be done is to install r100 on an usb key (C2 is portable).
Make sure that you backup your r95 projects before opening them with r100, and all should be cool.
In the case you would encounter some big bug in r100, you would "only" have lost the modifications you made in your r100 project.