Backup body for nature, street & travel

[Malsam]

Have been contemplating on having a small compact body to go as a backup for my nature, street and travel use. A little of the history...

Shoot mostly on nature and travel for the past few years and I discovered that I'm relying a lot on my cellphone especially with HDR and simpler handling. In October last year, I bought my iphone 4 as a backup to Bhutan and even though it acts as a "documenting camera" taking mostly dishes, posters, roadsigns, information on publication, the size and ease of using it make it very attractive and I listed one of these cellphone cameras as a "Backup of backup" since I carry them anyway I go as a utility device.

Now I'm thinking should I get one of those more featured compacts like G1x and equivalent (I'm not confined to a Canon model). Initially I'm thinking of getting another DSLR body, but has the disadvantage of carrying another set of accessories because the 5D2 just got an upgrade so unless I'm getting another 5D2 (which is quite possible) else it will be the 5D3.

Has any one has one of these non-DSLR body as a backup and how reliable are they as a backup?

TIA