I personally spend about 18 hours a week on IBL outside of class, but that’s probably one of the higher numbers, as I’m not naturally mathematically inclined. Some of my stronger friends generally finish the homework within three hours and type up their work as they go, which shortens the weekly commitment to maybe 10 hours a week, give or take a couple hours depending on if there’s a particularly hard proof. It really depends on the student’s ability (and willingness to get help) as well as whether you decide to do ALL of the homework or just guess which ones you’re going to present and get the rest of the proofs in class or during office hours. Some students do that out of laziness, some out of necessity from time to time. But try not to do it.
If you Google “uchicago boller ibl” you should come up to the original IBL scripts, although the scripts are modified slightly every year. You should be able to get a general idea of what the problems are like, though.
My class website for the quarter is here: http://math.uchicago.edu/~mcreek/spring_2016/math_16300/index.html so you can see the scripts we’ve done over the last two quarters as well as the general pacing of homework. Sometimes the workload gets really bad if we have scripts and problem sets due on consecutive classes, but oh well.
As for which class I’ve liked best so far, it’s a hard call. If I had to pick one, I guess I’d say the second quarter of honors compsci. I’ve both never been pushed to learn so many languages in 10 weeks as well as forced to have (and eventually gained) the confidence to code my own projects; it really taught me how to learn languages and stuff in general on my own and to have the confidence and curiosity to seek out the tools to create (almost) whatever I want, a skill and personal development I am very happy and grateful for. This is from the perspective of someone who hardly coded beyond AP Compsci senior year.
I also have very fond memories of my first-quarter hum class, and I love literally everything about my IBL class, even though it sometimes causes me incredible amounts of anxiety. All my bio/geo courses are all also just super fun. I also really enjoyed the content of my first-quarter compsci class despite not really being able to pick up Haskell at the time. In short, I’ve loved pretty much all my classes, so there you go.