Yes, the H100 is also very risky to flash.
The point about doing this though, is that once a known good version exists, that risk goes down hugely - e.g. the existing bootloaders that Rockbox releases have been tested a massive amount before release to make them pretty damn safe.
The real problem is developing and testing a new bootloader - if you make a mistake, you can only fix the player with specialist hardware, which very few people (and indeed only LinusN I believe) have. Once it has been tested and released, OK.