If this machine can run 16gb of ram are there any drawbacks?

I am running 8gb of ram on a late 2010 17" 2.53 i5 last 4 of serial number are DC7C

After reading the posts I would very much like to upgrade to 16gb of crucial memory! But I was told by a tech at apple that even if the 16gb of memory booted up the system may only use half of the available memory because of the 8gb limit. After reading your posts I wonder if they were just reciting the tech specs because they want to sell new models not enable older models to be upgraded beyond the specs that were published at the time. It seems you can answer this question!

I am a photographer running photoshop and this laptop experiences big slowdowns and freezes when I am editing large photos. Saving the photos while editing doesn't always help. I plan on upgrading to mavricks after I update all software possible and do a full time machine backup. If this machine can run 16gb of ram are there any drawbacks? Potential problems? As this is my workhorse when I am on location I don't want to lose it. Thank you in advance!!