Would be cool to have, still as "Echofon for Mac" eheh, the infinite/endless scrolling.
At least, especially for the main thing: the timeline.
In the future, can be extended for the tweets from a list, tweets from a specific profile, etc.
But for the main timeline only, it'll already be very good!
N.B.: Visibly, the potential problem may also be the limited API calls as seen on the first answer here: https://bugs.launchpad.net/birdie/+bug/1164266
=> but as suggested, maybe the streaming API can drastically reduces the total API calls as it's more an "event" system it seems. I don't know… but by luck, it'll be possible so! Especially because as the creator of the report in this link said, neither he has problems with popular Android Twitter clients nor I have with "Echofon for Mac" client. So, except if these clients have different usage conditions (maybe by paying or by seniority/popularity), it'll be possible too so! :)