Joerg mentioned in other topic, that cutting of power from microSD card slot, wehn card is in use, can - in rare occasions - hardware damage card. And he didn't mean dead loop of waiting for initialization but something pure-hardwarish about way that data is recorder and electrones Sorry, can't find this post right now.

What's the point is that removing battery = removing power from SD slot also (not big deal, cause unless you made hardware trick by sticking magnet to sensor, your card is already unmounted/hard powered off when your backcover is removed), but what's even more important, internal flash is also vulnerable to same hardware damage.

On the other (probably third at this time ;P ) hand, joerg also mentioned - in hotswap battery method - that bme shut down system in <1 second if battery is removed, i.e. control (third) pin is off. That's probably limit possible problems to single file damage, or filesystem error fixable by fsck at worse condition. If BME never fails in its duty, hardware damages are off-limit.

Don't ask me if same thing happen during use of HEN - as far as i know BME is stopped at this time, so i presume that unless we got working bme open source replacement, this may be extremely dangerous behavior during hostmode. But feel free to correct me, if any other entity monitor / hardware monitor watch for this in absence of BME. (still i think this is last defense line, cause stopping BME allow for hotswap)

Last theoretical divagation - if dme can be swapped out during heavy I/O bug so the phone reboots due to watchdog, who knows if BME isn't vulnerable to same swapout problem, -> in some VERY rare occasion of swap horror can not be able to shut down machine on time.

That's all theory (still, hard-proofed). In practice, If you don't feel suicidal and don't try to kill your device on purpose, it's almost impossible to damage device doing that. Almost. Although i fail to see any rationale for using this, when holding power button for solid 8-10 seconds (sorry again, don't remember exact number, may be also 15) launch hardware-controlled power down (in theory should be able to power down device always, like holding power button for 10 seconds in every laptop - in practice i heard about 1, literally 1 occasion, when even power button wasn't able to power down device and battery removal was a must - that's why on wiki is info about ''last resort'' method of removing battery)

// Edit

Was writing on exact same time as Robbie1ST, so sorry for cross-examining the same problems in few parts of my post. and thank You Robbie for mentioning NAND flash filesystem, that's also very important factor that i missed.