The effects of higher ability for higher chance to "proc" on crit/scholar isn't really huge. Maybe you'll see a small percentage increase like up to 5% which really can't be measured accurately, but it's certainly nothing as obvious as 2x or 3x more than usual.
Actually running a few tests today, I was floored by the results. My concern was before in a group others were procing just as much as I was with the xp rings. Pretty much one every three mobs someone would get an xp bonus. So this time I tried just skill crit rings, with my ability at 3890 in critical skill, in the three groups I had that day everyone was saying how much they were criting on their skills. There was only 2 mobs that nobody proced a crit on and were were killing fast ( fast for a level 156 with vender weapons and half bone armor) Some times 4 crits in a row just using skills. I dropped the rings and put on weapon crit rings and the skill crits virtually stopped for everyone with a few every other mob, At first I thought it was a coincidence but after I put them back on we all started skill criting again. I tried this a total of three times and the criting for skills went up for everyone in the party. Send one of your recruits my way and I will group with them. Kinda hard to find a group when people want to run and solo for loot all the time. In the meantime I will check em out solo, as far as i can see nobody really has tried and flushed out these rings out that much, perfering to go with what they know. Get a group of four people one with 4 skill crit rings, another with 4 weapon crit, xp and gold.
I am going to try this a few more times, but it seems to affect everyone in the group. This time taking numbers down, if this is the case then these rings are worth a lot more than I thought. I was just frustrated watching others in the group get as much xp bonuses as me but it seems like it affect the whole group. Again we only got a few bonuses for gold which is about normal once in a while, but everyone was hitting bonus for xp.