My own opinion is that I would only sell minerals or royalty if in immediate need of kidney or other grave circumstance. Harrison County is well situated in the productive area for multiple stacked plays (Haynesville, Bossier, Cotton Valley, Pettet) and should ultimately be a VERY profitable long-term asset.
As tempting as some quick cash might sound, these offers are generally for pennies on the dollar of the true value of the minerals in question.