hello, our attentive observer yes, it would be better having cumulative counters, but along with session based counters - both information is very useful for diagnostic purposes.
i admit, the snatch listing of grandtotal is sort of misleading in this place. right, there is no database field for storing per-torrent totals yet. however, your concerns about what problems it would cause, are out of concept the only problem that comes to my mind, is that this change might cause a great slowdown for the site, as it would require too many database writes {for each user, for each torrent}. i'm not sure if the current hardware is capable of it, as we can see great slowdowns during peek hours.
to correct some technical details: no, STOP does NOT erase your collected ratio. there is no need to keep your torrent not restarted until completion, as each stop automatically writes/adds collected ratio to your grandtotal. only the session counters get reset to 0.00. hence we strongly encourage users to close/stop their torrents before computer resets.
reset of session counters has two phases, timeshifted. as soon as the stop signal is received, transfer speed counters get reset first. there is no way to avoid it. but: if you resume your transfers in a short time after stopping, uploaded counters remain intact. the time limit is about 1 minute.
uTorrent does have the Downloaded field. right click the menu bar and enable it