[Epic 4G Accessories] bitbang3r:
An ideal Epic compromise would be more or less like you described -- an Innocase that allows the keyboard to slide out, with an optional exoskeleton that locks the keyboard in place and provides extra protection when desired.

HOWEVER, I wouldn't buy one unless it met two further criteria:

1. Silicone (or similarly-pliable-yet-firm) pads to transmit button presses from outside the case directly to the volume, power, and camera buttons inside the case. Protection from dirt and rain is just a nice side-effect; really, I just want it to give the phone a nice, even, solid feel that all the currently-available Epic cases (including Innocase) lack.

I really hate the way the cutouts on the Innocase (and, in all fairness, every other case out right now for the Epic) leave voids that make my fingers fall into exactly the wrong places when I grab the phone and try turning it on with the same hand. One finger (or thumb) ends up groping blindly for the power button, the other side gets supported by the screen, and half the time the shear force ends up pushing the keyboard open by the time the power button itself gets pressed... and the rest of the time, it makes the phone feel disturbingly "jiggly" and makes the phone feel like it's going to get dropped (if it doesn't actually GET dropped occasionally).

2. For the love of god and everything holy, make sure the case can be used with an extended battery. It's bad enough that the Epic's (and Evo's) batteries are criminally undersized and can't make it through a day of normal use without crippling the phone into annoyance and malfunction. Making users spend 5-10 minutes taking apart the case and phone to swap batteries would be a deathblow. Making battery swaps unnecessary for most users would be an ENORMOUSLY compelling feature.

If 3200mAH is too unwieldy for most users, consider meeting halfway -- sell the case with a replacement back and styrofoam padding block that will work with a stock battery, but can also take a battery with ~2200 REAL mAH of power without adding more than ~50% of of the stock battery's thickness... and bundle that battery with the case. If you read the huge thread about cheap extended batteries for the Evo at androidforums.com, two things quickly become obvious:

* Most cheap batteries alleged to be 2700-3500mAH are really ~2200mAH

* 2200mAH is nowhere near as good as Seidio's 3500mAH (that tests out to 2800mAH via the same methods that determined most of the cheap batteries were really 2100-2200mAH), but it's big enough to satisfy just about everyone anyway. If you read that same thread, you can sense that nearly everyone likes the "Chinese" battery back cover better than Seidio's. I remember reading quite a few posts from users who said they'd happily buy a Seidio extended battery AND buy a cheap battery from eBay just to get the back cover and use it instead (with a few going so far as to try modding the Chinese cover to fit over Seidio's slightly-larger battery anyway).

Assuming ~2200-2400mAH batteries that are ~1.5 times as thick as the stock battery exist, that's a nice compromise between the (admittedly) huge double-sized batteries and the inadequately-sized stock batteries. Given the inherent bulk a case with exoskeleton is going to have *anyway*, I seriously doubt anyone is going to complain about an extra 1.5mm of thickness if it means they can leave the battery charger at home and start using their phone normally again.

Idea: if the battery dimensions are somewhat constrained by stock sizes made by someone in China, combine two different sizes of cells and wire them in parallel... one size that produces a bundle the size of the stock battery, and another size that's larger, but thinner, and overflows the stock battery's footprint to make better use of the phone's rear surface area and spread out the volume over a larger area. Personally, I'm perfectly cool with having to remove the battery to swap microSD cards (so the battery can rest above it), because I run with a swapfile anyway, and Android will go down in flames and crash if I try removing the microSD card while the phone is booted up *anyway*.

The foam block is still important, even if the extended battery is included, because it will enable someone who has the rugged case and extended battery to still use his stock battery to fall back on in a pinch if the extended battery dies before the day is over.

A case like this would give Seidio something compelling and unique that no competitor is likely to offer anytime soon -- a total solution that bumps up battery life enough to permit easy all-day usage by most real-world users, permits keyboard use under normal circumstances, and enables the keyboard to be secured in place with an exoskeleton by users who don't want to use it at all, or who temporarily need to sacrifice it for the sake of protection.

Seidio has competitors that sell high-end cases (like Otterbox), but they don't sell batteries, and none of their cases can accommodate an extended battery. We all know that for stuff like this, the shipping, handling, and packaging ends up being a huge chunk of the total cost. By bundling it all together as a total solution, users can solve multiple real-world problems (protection AND battery life) in a way that's cost-effective and convenient.

The only way it could be even better is if Seidio got in touch with the guy who makes the GameGrip, and bought a batch from him that were customized to fit an Epic with Innocase-underbody when the exoskeleton is removed and the keyboard is out (with extended battery in place).