Yep, those 'jet & dimple' impingment designs look good, and very easy to make with the most basic of tools (woohoo!!
). The 3mm bases are a perfect thickness as well IMO. Thin enough for good performance bringing the dimples to near 1mm thickness yet sturdy enough to stop flexing/distortion...
I don't know if they are a perfect design for a large P4 heatspreader sized chip though, ????. Have you thought (or read) much about removing the heat spreader?...