I've used two different ones. Rago Brothers based in New Jersey for a dye job on a vintage (0-series) red camera bag. They did a great job, but this does change the feel of the lambskin leather. It was pretty dirty, so I was willing to lose the softness if it meant that it would have a nice, even, clean color.
Recently I used Leather Pros based out of Los Angeles and they did a great job on a lambskin jumbo bag (3-series) and I felt like their work left the leather a little softer. Prices were great too.
Both times I shipped the bags to them and they shipped them back. Took about 2 to 3 weeks.
I restore my bags myself with LMB products and some edge coat and smelleze if they are musty. I have not had to re-dye since I usually buy black bags. My husband kids me about how much time I spend buffing bags, but it is worth it. I actually enjoy it.
i've used leather pros in california, leather surgeons in nj, and rago. i'd rank rago last for customer service and quality of what they did (a redye). leather surgeons is very reliable and excellent workmanship, but runs expensive. leather pros was done very well, it was my first time with them and honestly, i think they did about what leather surgeons could have done, but a bit less pricey. always send pics first to any place and get a ballpark quote and text about what they'll do