Well,mine isn't a Cobra or an FE but just to share my experiance,I installed a solid roller in my Boss 429 and got about 1500 miles on it before a roller broke,wiped out the cam,and caused a total rebuild to happen.
The original lifters had no
oil hole to the wheel.
Being a glutton for punishment,I bought the same cam but with the "new" improved lifters with oiling hole to the wheel.
Worked fine,but the excessive seat pressure and the constant valve adjustement because of worry about another failure made me go to a hyd roller.The engine only lost 15 HP on the dyno and I'm not racing or running it above 6500 rpm on the street.But less maintenance is a big plus.
As for the sound of solids,I'll leave that for the track machines.
On the issue of dist gears,we drilled a very small hole in one of the front
oil galley plugs and aimed it at the gear.Constant oiling has got to help.