I built a small 2way (Dennis Murphy's MB1) with the GR Reseach GR130, which was replaced by the M130. The driver is a nice driver with a very good midrange and very good bass response for a 5.5in driver. Due to their baskets, they have to be surface mounted. For the price, it would be very difficult to find a better driver. I have not used the 6.5in driver.
Hope this helps.