Solids make power & rpm. Maintenance on mild streetable grinds shouldn't be a problem either. In the past I've used solids in both wedge and Hemi engines without any problems.
Now we have new issues to consider that we didn't have years ago. Flat tappets solid or hydraulic are failing much more often than they used to. Rollers are the obvious solution to this problem, but I have real doubts about solid rollers having 100,000 mile plus reliability, which is my personal definition of true streetablity. I think that even with relatively weak spring pressures the axle bearings on a solid roller will be hammered pretty hard due to the required valve lash. OEM hydraulic rollers on the other hand have proven to have good long term reliability.
Aluminum heads, we didn't have them years ago. Now we do and they're great. Light weight, good flow OTB, easy to repair, less time involved in porting etc. They also expand and contract more than the iron blocks they're bolted to. This of course affects valve lash. I don't think that this is a real big deal, but it is one more argument in favor of hydraulics.
I am presently using a Comp 284 xe flat tappet hydraulic in my aluminum headed small blk. I expect it will be the last flat tappet cam I'll ever use. Next time, hydraulic roller.