Regulators

[jevans]

Are there any special considerations when choosing a reg for a pony tank? What's the current equipment trend for something you hope you dont have to use?

[jasondbaker]

I would use a reg that is the equivalent of your primary and secondary regs -- sealed and designed for cold water use. You may even want to swap the pony reg for your primary once in a while just to get some wear on it. You would hate to be in a situation where you need that untested pony reg.

[DRE]

If you don't plan on using it, then why bring it along?! I'm sorry if I sound somewhat ignorant when it comes to using pony bottles (I never have and I never will), but if you plan your dive and stay within your gas limits you don't need a pony. Also, in the remote case you run out of air (or low), you should always have your buddy nearby who can assist you with whatever gas needs you might have.
IMO, a pony adds nothing but drag to your rig, which means your gas consumption will increase.
If you plan on using the extra gas, then you might as well start using doubles (double AL80's don't weigh that much more than a single steel with a pony, and it'll probably even be cheaper!). If you plan on using your pony for overhead wreck dives, doubles are definitely a must.
In case you want to fill the pony with a higher O2 content for accelerated deco, then I would recommend buying an AL 40 and slinging it as a stage (something like this could also be recommended for ice diving). It'll give you much nicer hose routing, and it'll sit nicely in the slipstream already created by your body.

As far as the reg recommendation, I second Jason's input. Just buy a nice reg (no use waisting your money on useless gear you'll throw out anyway), so if and when you move to a doubles setup or a stage bottle setup, you'll have a reg equal to your primary.

Feel free to contact me with any other questions you might have.
Best,
David.