It would be nice to have an option to offline allocate/allocate without transfers active (more aimed at the full prewrite/fast allocate modes).

Couple ideas:
* Ideally on a per-file basis, maybe under right-click menu -> Local Files -> Force Allocate (beside force check)
* checkbox added to preferences to disable all up/down of all if anything is allocating at all, like 'Transfers temporarily halted during file allocations' checkbox, or a 'Instant allocate on New Transfer Add' checkbox, etc.

Reason why is I will lets say add 10 1-gig sized torrents. It will allocate torrent #1, start it transferring while allocating torrent #2, start #2 transferring while allocating #3, etc. Without manual intervention to pause/stop, etc. with a limit of 10 active transfers, you end up with all the previous transfers thrashing against the allocations, increasing time of both to more than if they are done one after the other. Lots of bonus harddrive thrashing wear and tear and higher possibility of filesystem fragmentation of the larger files. Would be nice if they are allowed to allocate with no/minimal competing reads/writes active meanwhile.

That is true. While allocating, it keeps track of 1-by-1 files ...
It wrecks hell with the rest of your stuff on that drive.

Or perhaps this is another instance where the single bus-speed thrashing shows how bad it can get?

I agree there should be some tradeoff here.. either an option to "only down/up" vs "allocate new transfers" ... or force some sort of different-disk logic for "best performance"