I own a Saiga .223, and I weighed the pro's and con's heavily before choosing it over the 7.62x39 model.
Pro's:
As reliable as any other AK
Ammo is commonly available in the US and reasonably cheap (convenience and availability; a simple import ban won't cut me off)
All ammo is non-corrosive (convenience and SHTF; you may not be able to regularly clean your rifle in an emergency situation)
Ability to use US military ammunition (SHTF)
Tend to be built a bit better than other AK's, and more accurate (newer production in modernized factories)
Ammo quality varies much less than Combloc production (even the worst Wolf ammo will usually be on par with the best surplus 7.62x39)
Con's:
Magazines not as common (US-made magazines ARE available, and wear parts such as magazine springs are universal)
Ammo is more expensive than Commie surplus (however, you lose most of your savings on cleaning supply costs due to corrosive primers)
Spare parts are less common (bolt and barrel differ; most other parts can be swapped with an AK-47. It takes a LOT to screw them up)
The benefits, in my opinion, far outweigh the drawbacks. I look at a 5.56 AK as a better alternative to an AR-15. It's a totally different technology base, but it's one that's more reliable and less flaky. I consider the very real possibility that I may not be able to properly clean my gun for a long time. The fact that it will keep running, and shoots non-corrosive ammo is a huge winning combination for me.
Now, on the peaceful side of it:
Plinking and hunting: I equipped my Saiga .223 with a scope, and am consistently hitting 2" patterns at 100 yards. I intend to use it to hunt smaller game such as javelina. I could use it to hunt deer, as well. It's a good shooter and a very solid all-around rifle. It's a lot of fun to shoot, too. It's accurate enough to do whatever I need it to do within the effective range of the .223 or 5.56 round. The people next to me with the low-end AR-15's (that kept malfunctioning) were shocked to see me matching their patterns. Funnier still because they paid easily twice what I did for their guns; their guns were malfunctioning all day, and I have yet to have my Saiga jam once.
Trunk gun / ATV saddle: Almost invariably, a gun that is practical for compact storage will be less practical in all other uses, and the same is true here. Such compact setups usually have shorter barrels than are optimal, which will reduce the effective range. If you can get by with a 16" or 20" barrel with or without a folding stock, they will certainly work fine for this. Keep in mind, though, that if defense from bears is what you need, you should go for a larger caliber weapon.
