I don't think there is much rsik in updating. The UI in X3 is not a whole lot different than X1, so the transition should be smooth and fast.  You can pick up new learnings as you go.

There are actually some fairly significant differences that could impact workflow, depending on how you work. If you use the piano roll view a lot, for example, that changed quite significantly in X2 in terms of overall behaviour. Also, the way you select stuff in both PRV and Track view changed, with Right and Left mouse click behaving differently from before.
 
I don't think these are massive scary changes, and I think they were both improvements, but it's not like you'll just sit right down and carry on as before. I'd allow yourself a session of a few hours just to get used to these kinds of things.

Thanks again. it sounds like x3 is cool, but (given some of your advise)I may go ahead and finish this project and then upgrade.

I actually have a whole CD (waiting on one element for one song) finished in X2.  I've not opened them in X3 and have no plan to, because I'd want to switch some effects and from there I'd start re-mixing.  As Dirty Harry said, "A man has to know his limitations."
 
But other than my weakness, there is no problem switching versions mid stream.  Unless you are stepping up to X3 producer, in which case Breverb will be much better than whatever reverb you are using in your old project and a few other fx.  In fact, the above CD was switched from X1 to X2.  It is just that X3 arrived when I was finished.
 
There are a few ergonomic changes between X1 and X3, but you will want to learn those anyway.  If you have a deadline, these may cause you to invest a little more time in the project, but otherwise X3 Producer is a much better program than X1 Studio.
 
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I think this all starts to stray into the area of "how to finish stuff". Myself, I never upgrade anything in the middle of a job, because it's not related to the goal of "finish the job". There might be some better tool kicking around, but that's for the next job. The pursuit of the best tools is never-ending, and only pauses when you choose to pause it.

I think in between X1 and X3 quite a few of the keyboard shortcuts and menus have changed. I wouldn't change to an upgrade or even an update if I had work to be done.

I always quarantine new versions. Get some familiarity before committing myself to using it.
Always finish work I'm doing in the version I'm currently using and never do any mission critical work until I've checked out bugs and workflow and approved it for my use.

If you're making a living do this you need to approach using your tools in such a way as doesn't hamper getting your desired results