Another possibility of course is to increase your RSS refresh time - say from 10 minutes to 30 minutes or more. Not perfect, but will decrease likelihood of catching stuff not complete on your server.
Actually, for most purposes, RSS is bettter checked just once or twice a day, IMHO. Autodownload makes most sense when, for example, grabbing overnight releases, in which case checking the feed once in the morning (depending on timezone) is usually enough. I just do it once at 9.00am GMT, for example, and that's always worked well for me (needs a scheduled task though). For anything else, the Import as Paused option may be preferrable. I seem to remember an open request about adding that as a per-filter option.
Newzleech I would say is one of the least useful RSS feeds to use for this reason among others - it updates too quickly, and with too many results. Really you need to decide what exactly you need autodownloading for, and pick the feed to suit. There's a nice range at nzbs.org, organised by release category, and there's a relatively long delay on them to ensure completion (especially for x264).
There are some interesting ideas here about queue management, though, even if they are complex. Personally, and for other reasons, I'd be +1 on the ability to expand the queue to see article parts for files. I presume it's the way it is now because the yEnc decoder needs them all to be able to function, and this is the easiest way of ensuring that.
Let me add another request on the back of yours: expand the refesh intervals, preferrably to allow setting specific times rather than just intervals. So, perhaps a bit like setting a cronjob, using minutes, hours & days of week (0-6):
0,20,40 * * = would check every 20 minutes every day.
0 9 * = would check once at 9.00 am every day.
30 8 1,2,3,4,5,6 = would check once at 8.30 am every day but Sunday
Or something like that. Edit: would probably need to add a random number of minutes to prevent server hammering by everyone with the same settings.