Just want to mention some things unmentioned so far(and a rehash of one that has been^,^;):
1) HD Advance 2.0 comes with 2 discs, but each has the same software, so essentially if you have to persons with HDDs installed on their PS2s they can both use the software at the same time.
2) The only reason there are two is to allow you to backup burned and import PS2 CD and DVD games without having to install a modchip in the PS2 which which is copying the games. (??? tell me if I am wrong so I can hang myself ^,^;)
3)The HD Advance 2.0 discs already have versions of the updates that can be downloaded separately for HDLoader, eliminating the need to mod your PS2 to install the files as you would have to do with HDLoader.
4)HD Advance 2.0 supports certain (hey, I only know it's true, I'm only using the official Sony HDDs as is) third party HDDs of sizes up to 200GB.
So it might (my uncertainty is a cry for support for either side of the comparison T.T) make sense for the more average gamer to get HD Advance 2.0 for a whole five dollars more as opposed to HDLoader and a mod chip (or a modded PS2 if you have shaky hands :p ) as it would be easier to get started. I have not yet used HDLoader, but I suppose that since it could likely have a wider range of compatible games it has more bang for your buck. Depends on the person's situation. Me, I'm happy that in a week I can test both HDLoader and HD Advance 2.0 against one another, or rather, just use them both. And I expect neither will be a dissapointment. ^^
Oh, and on a more obscure note, but one that may help those looking into purchasing HDLoader or HD Advance, both are unable to copy both layers of dual-layered DVDs. You need to install those games (Champions of Norrath, etc.) by hooking your HDD up to your computer and using your DVD-ROM/RW to install both layers of the game. Directions for this procedure can be found in the HDLoader FAQ located on the compatibility page for HDLoader at:
http://homepage.ntlworld.com/casey.m...patibility.htm
Have fun. ^^
Oh, and it seems you can install import and backup PS2 discs by using the same procedure used to install dual-layered DVDs. Just a guess from adding up information seeing as how your DVD-ROMs will ignore region coding checks.