Certainly, thought rigor. I've been constantly testing every damn thing I do, be it research, leadership or what have you. What might have been a previous gut decision in work with groups now involves testing the motives of all involved, including myself, and being incredibly weary of any viewpoint that seems like a shortcut from myself or others.
The evaluation of others has certainly been improved- Predicting and rationalizing others behavior has become a lot easier (In at least one case allowing me to cherry pick co-workers for an assignment when I really should not have been able to), and I'd like to think I'm slowly working through and against general attribution bias.
Also, fear of failure/Want to get out there has reduced significantly, to the point where opportunities have come floating by every other day now. Unfortunately this has developed an acute Fear Of Missing Out, and I've reached the point where I need to cull responsibility... Too many unfinished projects and not enough time.
Related to: Tsuyoku Naritai! (I Want To Become Stronger), Test Your Rationality, 3 Levels of Rationality Verification.
Robin and Eliezer ask about the ways to test rationality skills, for each of the many important purposes such testing might have. Depending on what's possible, you may want to test yourself to learn how well you are doing at your studies, at least to some extent check the sanity of the teaching that you follow, estimate the effectiveness of specific techniques, or even force a rationality test on a person whose position depends on the outcome.
Verification procedures have various weaknesses, making them admissible for one purpose and not for another. But however rigorous the verification methods are, one must first find the specific properties to test for. These properties or skills may come naturally with the art, or they may be cultivated specifically for the testing, in which case they need to be good signals, hard to demonstrate without also becoming more rational.
So, my question is this - what have you become reliably stronger at, after you walked the path of an aspiring rationalist for considerable time? Maybe you have noticeably improved at something, or maybe you haven't learned a certain skill yet, but you are reasonably sure that because of your study of rationality you'll be able to do that considerably better than other people.
This is a significantly different question from the ones Eliezer and Robin ask. Some of the skills you obtained may be virtually unverifiable, some of them may be easy to fake, some of them may be easy to learn without becoming sufficiently rational, and some of them may be standard in other disciplines. But I think it's useful to step back, and write a list of skills before selecting ones more suitable for the testing.