The problem with HDLoading on phat PS2's is that you're limited to EIDE/PATA hard drives, and what manufacturers make that anymore? WD... and they intentionally space out the connectors so that they don't fit in the PS2 network adapter's ports anymore. You'd have to mod the connector to fit... or try to find another brand that makes PATA drives still, which is not easy. Makes me wish I jumped on that Hitachi 1TB PATA they had now, as my 160GB one's already full up.
I have a Matrix Infinity with 1.93 firmware on it. Pretty much can load anything on it, and direct boots PS1, PS2 backups fine. Also had the extra wiring put in for DVD±RW backups, though rarely use that now with DVD±R's being so cheap.