Actually, Rhodium, I'd rather 'over-tartrate' because excess HCl can ruin many products, creating toxic (or otherwise poisonous) by-products. Using the selective solubitilies of the tartrate salt and the acid itself, you can filter off excess acid. The HCl, although you can evaporate it off, it's not necessarily a good idea (as mentioned above). Plus, you'll need to recrystallize the product anyway (especially if you are over-titrating).
thoughts?