Hello! I love your products and I use them a LOT. I am an engineer and have a few suggestions:
1) have a pull string attached to the Lithium Ion Battery Packs so they are easier to pull out to load
Agreed, that would make it much easier to pull the battery and other electronics out of the sabers.
2) give the batteries a little more wire! if you take them more than an inch out of the saber you risk damaging the wiring because they are so short.
Not the easiest thing to do in a confined space, unless the batteries have no wire at all, instead having a connection plate or tabs.
3) the LED rattles in almost every saber i've held unless it was just pushed down. Add an o ring or some padding there.
A foam incert or something that could hold the LED module would be a great addition to the sabers.
4) make the top parts of sabers interchangeable just like the pommels are. People would buy more of your cheaper sabers if they could swap out emitters, shrouds, etc.
This would require an entire redesign of the cheaper sabers, but at the same time would push those same sabers into a higher price bracket, thus they wouldn't be the cheaper sabers anymore.
5) Make your blades threaded. I have a Bellicose with a blade holder and I had to machine additional holes for retention screws to avoid a rattle during vigorous sparring matches (i'm in a group that competes with them at fencing schools).
That would require an entire redesign of every saber in the line up, and it would ultimately add to the cost.
Another option would be to affix some electrical tape to the socket end of the blade, it gives the set screw something more to bite into, plus it snugs up the blade a little more.
6) your basic sound board is a $100+ upgrade, and yet the saber does not have a mute button? I would have spent 100 bucks to make mine have basic sound, but i don't like that i don't have a Volume Control or Mute. A 3 hour long flow or sparring session will make you get really annoyed with sound fx, trust me.
The V4 sound board has a mute option, and the Diamond board has a volume control.
7) Sell customization parts and kits such as leather to wrap the hilts in.
Agreed, some more customizational items would be a great thing, like button screws, and so on.

the covertech wheel is too big and gets in the way of my grip. How about an option to have a clip on the bottom of certain pommels? The old school original graflex sabers used in the movies had a clip like that and it doesn't get in the way of my 2 handed grip.
If you don't use the covertech wheel, you could always remove it, and replace it with a button screw, or leave the hole.
9) whoever you buy your caps from, ask them to make them more transparent and machined to be more even! Every blade i've bought, the tip is slightly off center to one side and is also a much denser look so it stands out like a sore thumb. Props for making them threaded recently, though!
The tips have a reflector in them to reflect the light back down the blade, this could be why they look a little off.
That's my wishlist
That's a good list.