I know this is an old post, but for anyone browsing this in the future, YES, it's worth doing the OpenCore. I'm running Monterey on a 2011 iMac with quad core i5 that I upgraded to 32GB RAM and 512GB SSD. It runs flawlessly and the OpenCore resolves the "Metal" incompatibility. No need to upgrade the video card, it works fine.
OpenCore now supports Ventura, but since that OS is only 4 months old I'm in no hurry to upgrade.
The photo below is lousy but you "get the picture".
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