There are plenty of plugins on wordpress.org but perhaps a “Scroll to top” add-on would be helpful and thus avoid the need to search for an appropriate plugin. This would assure that the code is to your high standards and maintain the performance that your members have come to expect from GP.
Been thinking about this – I wonder which add-on it would fit with? Seems like a waste to add a whole new add-on just for the one feature.. Maybe Menu Plus?