I run both. I prefer the jewel over the timney. I like the thinner trigger as well.
Yet with the timney tuned up right, they are still a very good choice over factory. I have had no problems getting mine to right at 2 lbs. I have 2 of the 510 and one 512.
I have 2 jewels and for going under 2 lbs I like them better. Both of them are set at 1.5 lbs.