I’ve only taken a couple of day tours with Rabbies, but I have been researching the multiday tours as I plan to take a couple next year.
The reviews for Rabbies are generally very good. One negative complaint I have seen a few times is with the location of the accommodations that they book. I have seen a few comments about the lodging being outside of the city center and away from restaurants. Because of these comments, I have booked my own hotel for the 3-day Ireland tour I am taking next year. So, you might want to consider booking the accommodations yourself. I do think the earlier you book, they can probably get you better accommodations.
The thing I like about Rabbies is that when you are off the bus, most of the time is your own. You are own you own for meals, so no group dinners.
I have found them to be well organized at the departure location and very responsive the few times I have emailed them questions. I like the small size, with a max of 15 or 16 people. There were always plenty of opportunities for bathroom breaks and snacks/meals.
I would not hesitate to book a tour with them. Good luck deciding. And if you do take the tour, I’d love to hear about it. They really have a lot of good options.