Need to install minimum 10.9.4 for XCode, but running 2009 iMac with 2GB Ram, only option now is Yosemite been given a iMac to configure for my new job.

Its a 2009 20" iMac. I recently clean installed Mountain Lion, as I knew it was stable and I had a boot USB.

I thought Mountain Lion would be enough but now it turns out I need to upgrade and can only now be Yosemite....

My question is, will Yosemite be too much for my 2009 older iMac with 2GB Ram?

Currently it runs fine, and ram can be upgraded to 4GB but not for a while.

Thanks. Craig,
A friend of mine recently upgraded his MacBook5,1 (2009 core 2 duo) with 2GB to Mavericks. It wasn't the most pleasant thing, but it actually didn't work out too bad for him and he even thinks there was a slight performance increase (I'm assuming due to the memory compression stuff being a touch faster than swap). I'm assuming that Yosemite isn't going to be much more stressful than Mavericks, so you can probably get away with it.

That being said, 2GB is absolutely too little for a machine that you're going to run Xcode on. Regardless of Mountain Lion, Mavericks or Yosemite, you need more RAM. Period.