My auto correct to English dictionary tells me that you lost a lobe on a solid flat tappet and would rather not do that again.
So much for artificial intelligence.................or it would know that I very rarely type " duck ".
I have not run one........I have a solid roller that sees street miles and has been trouble free.
My understanding is that they are pretty critical of spring pressure and lifter pre load compared to a hyd. flat tappet.
But I think that if they weren't worth a dang , the OEM's wouldn't have them in nearly every motor that leaves the assembly line.
Like anything else , stick with quality parts and you should be fine.