I can vouch for the cheap Chinese sata adapters being good - I've been using one I bought off of Ali-Express for a couple of years with no problems (and I regularly remove and replace the drive to hook it up to my pc).
As someone else mentioned, FreeHDBoot is an excellent replacement for FreeMcBoot on a memcard, but I would recommend keeping a memcard with FreeMcBoot on it in case you ever have an issue booting directly to the HD.
You almost answered my question. I was gonna ask if its ok to keep the memory cards with Mcboot and use it for FMCB even when i already have HDD.
Another thing, a lot of tutorials in my research seems to prefer to use the HDD as well for saving games. But i have 128mb memory card for saving and such (with my current save files too). Is it still gonna be usable after i went to HDD on network adapter?