Gogol: boiled down, the question is can I assume I can draw 75 mA from the 5.5v pin (assuming I have appropriate power to the Digispark Pro). Since I blew out a Digispark in the same setup, I thought I would ask to be sure I could do it with the Digispark Pro without risking letting the magic smoke go. When I posted the question, I hadn't dug deep enough in the KS posting to notice it has a 500 mA LDO to regulate voltage, I would actually hope I can draw out up to 400 mA if I have a power supply that delivers an appropriate amount of current.
DeuxVis: I have several batteries that provide USB level output like the one you mentioned, plus li-poly batteries, multi-voltage batteries that provide a USB output plus regulated voltage up to 12 volts, 9v non-rechargeable batteries, and AA battery packs up to 8 cells. Which I use depends on various other circumstances.
For example, I have one setup where I have a squirrel finger puppet that is dressed like an artist, and her canvas is a small lcd that is fed from a security camera, and the camera/lcd prefer 9-12v over 5v, so there I would prefer to power the micro-processor with 9v, so I have a single battery supplying both parts.
On the other hand, for smaller costume pieces like my steampunk goggles or bow-tie, I tend to prefer li-poly batteries because the batteries are so small compared to an AA battery pack or USB cell phone charger. I'll have to see whether the li-po shield adds too much bulk to be usable for a small piece.
While I can wire up a digispark programming tool (
http://digistump.com/products/42) or similar to have additional lines for raw power, I would prefer to keep things as simple as possible (more components means more things can break, and in a costume the more separate components there are, the more likely one is going to become separated by the end of the day due to vibration).
As I said, I do have batteries that provide 2 power levels, but those tend to be big and heavy. I tend to prefer having one battery, since it is simpler to replace the battery, while if I have multiple batteries, you have to determine which battery has become drained to replace, and with multiple batteries, it means you need to carry spares for each battery.
In terms of the 5v batteries meant for charging cell phones, I have several of these, but the newer ones seem too smart, in that they will automatically cut off if the 'cell phone' (i.e. micro-processor) is not drawing enough energy (or it doesn't identify itself as a phone). I've seen circuits like this that fools these type of batteries by using a spike of power every so often to fool the battery to stay on (but not enough that it drains the battery faster):
http://www.dorkbotpdx.org/blog/paul/battery_pack_load
