I replaced the original Groco head in my '89 Pearson 31 with a new one. The original one had a crack in a flange on the pump, likely a stress crack. Groco has improved the design by changing the the bottom tube on which the bowl and pump mount from plastic to bronze. The unit should then be much more robust. The inlet and outlet attachments for hoses were in the same places which was important. Installation of the new head was straight forward. The only issue was that the spacing on the mounting tabs was changed. Two of the tabs lined up with the original mounting but two new holes were required at the opposite end. This was not an issue in my boat but could be in some. After installation the head worked without any problems.
We have cruised 15 years with this Groco head. Sure, we have replaced wear parts about once every three years and currently need a new pump cylinder due to cracks in the plastic. But, this head is easy to repair and for the cost appears to be a great value to us.
I would rate poor. We use on weekends only. last about 3 months before problems, water backs up in toliet, looses prime. Good news, they rebuild for free. I have 4 pumps that I have rebuilt at least once per year. Always carry a spare when on a weeks trip.