No experience with TriggerTech, but have 7 Jewells. Never had a failure in the field. Once a year, I'll blow each out with brake cleaner, lubricate with lighter fluid and blow out any excess with canned air. They are very consistent on pull weight and I've found them to be totally reliable.
I've bought all mine from Larry @ GreatScott Shooters. Great guy to deal with.
I run Jewells on all my 700s and 700 clones.....hunting/guiding in dusty, windy South Texas..... never a problem in the many, many years I’ve been using them. They get plenty dusty riding around in Rangers and Top Drives. I blow them out with my air compressor every few days of use and clean them with lighter fluid after the season. I had a TT come stock in my new Cooper Backcountry and couldn’t get it to adjust below 2.5 lbs. I called Cooper and TT and they both told me that the firing pin spring on Coopers were too heavy to adjust the TT down as light as it should adjust. So I ordered a Jewell for it, set it at 1# as all my others are set(accept for my 13# CM that is set at 10 oz) and it was good to go. Mark at TT was a great guy to work with and he sent me the Special Trigger and I sent him the Cooper original TT back. I put it in my CM which is built on a 1970s 700 action that had well over a 1000 rounds through it as a 25-06 before rebarreling it to 6.5 CM. The Special Trigger would only adjust down to 1 lb 9 oz......I guess the spring is to heavy in this old action, as well. So I guess I’ll try it in another rifle eventually but as of now, I’m a little disappointed in TT! The bolt release lever is also a little flimsy compared to the Jewell. I sure like the TT concept and was wanting it to work, but for now, I’m sticking with my Tried & True Jewells!!
I have had a bunch of Jewell triggers on my hunting rifles for the last 10 years. Never an issue. I recently purchased the top of the line Trigger Tech Diamond and man is it sweet. Not gonna lie, I like the feel of it better than the jewell's I have. The only thing I would like to point out is the Jewell's are adjustable for creep, over travel and pull weight. The trigger tech's only adjustment is pull weight. It has absolutely zero creep so obviously thats a non issue but it doesn't have much over travel so keep that in mind.
If you want a slap in trigger, trigger tech is great. If your one of those people that want full control over adjustment you have to go with a Jewell. I own Jewells and no trigger tech triggers but I do have experience with them as one of my shooting buddy swears by them, so I get some trigger time on them and like them well, but I'm not about to sell my Jewells and change them out. I must also add that I out shoot him regularly hahaha