Money vs Horsepower
No matter how good the parts are, there is no way a hydraulic lifter of any type can make equal power to a solid of the same type. It's because part of making power is the rate of lift off the seat, and the closing rate. Because of the shock absorption of a hydraulic plunger, and the fact that eventually the required spring pressure will collapse them, they just can't be made "the same". And because of that, they will always be a little short. Hydraulic roller lifter engines lose lift, lose stability, and lose rpm simply for the pleasure of running those lifters. The rpm loss is the only really "feelable" loss, but loss they all are. Coupled with the cost of buying them and the cam I rarely use them. They definately have thier place, but certainly not the be all end all.
Just out of curiosity - and maybe for a new thread... The guys that have hydraulic rollers and had thiers dyno'd... what was your highest output per cubic inch in terms of naturally aspirated hydraulic roller engines? Please give basic engine build stats too.