Bobby, welcome to LTG.
I have not had an opportunity to A/B my Tacoma-built F512 with a Westerly-era F512 or JF55-12. I can only tell you that the Tacoma F512 (and I've played two of them) is built to older Guild specs from when the model was young back in the '70s. The body's a little thinner than an '80s Westerly, but I think slightly wider.
Tacoma has tweaked around with the a few things, including the bridge, saddle, and pickguard, and I like what they've done. I've seen no construction issues with the Tacoma F512s to report to you. My 2006 is built great. The 2008 I checked out recently just seemed to lack a little luster in the look of the spruce they used on the soundboard, but it played beautifully.
Since I can't compare tone with a Westerly F512, I will only tell you that my 2006 is the most responsive and flexible 12 string I've ever played. If you're comfortable with a Westerly 12 string neck, you'll be comfortable playing a Tacoma F512. Playability is "like butter" if you ask me -- certainly for a 12 string.
Whether you're finger picking or strumming, this guitar sets a standard for all other 12 strings to aspire to.
I created a thread recently on 2007/2008 changes... You might want to look through that to see if any of that is important to you (regarding buying a new Tacoma or a used one).
Best wishes.