I am working on (and by "working on" I mean, I created some messy code 5 months ago and then abandoned it but cling to the dream that I may one day finish it) something similar, but wanted a web based UI - I have the same issue whether it is on a mobile client or at my desk. I want a twitter client that is smarter than a linear display of what's going on - and instead figures out the context of tweets (like replies and retweets) and intelligently gets me that context
It looks like you are trying to solve that issue with replies, kudos to that.