So I'll let someone else comment on its viability.
Your comment, "it might be better to purchase a Mini DV AVCHD camcorder" is invalid. MiniDV tape does not store in the highly compressed AVCHD format. For high definition, it stores to HDV (and for standard definition, to DV). HDV is much less compressed than AVCHD.
Since I never know where I'll be for video capture, I try to limit potential issues... hard drive based camcorders have know issues with lots of vibration (very loud crowds, very loud engine noises, very loud music - amplified or not) and high altitude (over 9,800 feet). The heads will park and no recording happens. MiniDV tape and flash memory based camcorders do not have these issues.
The camcorders you listed, have small lenses and small imaging chips
HDC-SD9 - 37mm lens - three 1/6" CCD chips
VIXIA HF100 - 37mm lens - single 1/3.2" CMOS chip
HDC-HS9 - 37mm lens - three 1/6" CCD chips
If you have changed your requirements (removed "good results also in low light") then any of these will be fine. If I can't have miniDV tape, then I'd go with flash memory.
For archiving, you will always have a bunch of whatever it is you choose to archive to... Having been an IT manager in a previous life, I trust digital tape a lot more than hard drives or optical disc.
If your version of Premiere can handle AVCHD encoded files, then all you need to do is copy the video files from the camcorder to the computer. There may be decompression time required.
For YouTube posting, if you want high quality files, use the file format suggestions at vimeo.com. As a h.264, 720p file, the files uploaded at vimeo and YouTube can be the same file. Depending on the length of the video and your computer's CPU, rendering can be fast or really long.