Adjustable rockers allow you to adjust lifter pre-load with a hydraulic cam, or lash on a solid cam.
Higher ratios rocker arms allow more lift at the valve which makes the cam seem a bit larger.
The roller tip rockers are supposed to eliminate the rubbing action across the tip of the valve stem. This feature is more important when using higher lift cams with higher valve spring pressures.
Full roller rockers with rollers on the rocker shaft are supposed to help reduce friction.
The stock rockers do a good job, but the actual rocker ratio is less than 1.5:1, and with higher valve spring pressures, the pushrod can break through the rocker arm. They are also non-adjustable.
On a small block, if you goto a higher rocker ratio like 1.6:1, you should enlarge the pushrod holes in the cylinder heads, because the higher ratio comes from moving the pushrod closer to the center of the rocker arm.
You will likely need new custom length pushrods too.
As for the quality of rocker arm, alot depends on your valve spring pressures. I have a friend who is running those rocker arms on a really mild (near stock) engine and he says they are fine?
I bought a set of the identical looking "CAT" rocker arms for my 440, and they had issues with the roller tips wearing. I think the stainless bodies of the rockers are OK. They had good geometry, but really to be useful they would have to be rebuilt with hardened roller tips and pins, and the adjusters replaced with better quality ones. Anyhow, I learned my lesson and I'm running Harlan Sharpe rockers on my 440 now.