Is there a reason you chose the percentile instead of something like the pivotal (and for not adding the options for other intervals)? Is it solely for simplicity?
Excellent q - we intend to add in other options as we go. Pivotal being one. Id also like to add in permutation tests. If you have ideas we welcome diffs =)
Would love to contribute. I'll try to put some work in this weekend when I have the time.