Waterproof Messenger Bag - recommendations?

vermin Posts: 1,739
edited April 2015 in Commuting chat
Since my normally trusty North Face messenger succumbed to the two-hour soaking on Monday night, letting water in through the porous back panel, I have been hunting around for a fully waterproof alternative.

The two I've found so far are:

1. The Aquapac Stormproof Messenger Bag - which looks good but is rendered useless by the omission of a stability strap.

2. The Freefold CTS Messenger Bag - which has a fully waterproof roll-down closure and a stability strap, but the stability strap doesn't look very convincing (seems to attach to the top corner of the bag rather than the bottom corner, leaving the bag less tightly secured around the rider).

Has anyone any practical experience of either of these bags, or are there any other fully waterproof options?

I'm not a fan of rucksacks for my commute.