Mathmatistically wise, 1.650 is closer to 1.625 than 1.687, ja? But them joints be hand sanded so there's always gonna be some variation. I haven't played a 1.65 yet, but I want to - it seems like a good compromise. I can't wait to get back on stage and scream "DO YOU UNDERSTAND THE NOTES THAT ARE COMMIN' OUTTA MY 'MOTH?"