It is not the best really. You will notice a big boot delay if you do that,
False.
3.9 already does this and it so fast it is almost undetectable when booting from CF.
and then if you dont have a MMU to protect the memory space where the kickstart is, some program, most likely a patch will probably corrupt that memory area, and guru your Amiga.
False.
Just about everybody that uses 3.9 IS softkicking (except the 3 people that have burned their own 3.9 rom). So this seems very unlikely.
Another drawback, especially for low end sistems is that you will loose as much memory as your rom occupies (512KB, 1MB or 2MB depending on this new kickstart size).
True, but we are talking about people wanting to use a 3.9 kickstart. If you are using 3.9 you have a ram expansion.
If your disk gets screwed someway, bye bye kickstart.
So there are a lot of disadvantages, and much more that I dont remeber right now.
Again this is ridiculous. First of all the kickstart ROM will always be on the motherboard. If your harddrive crashed I think the last thing you would worry about would be a kickstart image file.
This whole posts sounds like you are posting fud.