I think it depends on what you get. The very fast SSDs get hot. Heat is the enemy of all electronics. For me even the slowest SSD is worlds faster than any HDD.
The thing here is HDDs are one bump away from data loss. Maybe I accidentally bump into my PC case. Now I'm looking at replacing the HDDs while hoping I backed up all my data. That's my reliability concern. The smaller the bits get, the more easily the whole thing is rendered useless by a little bump or vibration.
Then there's power consumption. The 5400 RPM HDDs are around 5 watts, which means 7 or 8 from the wall. The 7200 RPM ones are probably north of 10 watts at the socket. With as much storage as you, I might be looking at a few hundred watts just for the HDDs alone. Heat aside, I couldn't afford the electricity. Current rates are around $0.35/kW-hr but we'll be over a buck a kW-hr if ConEd gets its proposed rate increase approved. Even at current rates, the power bill would be like $750 to $1,000 annually just for the HDDs. That's not counting the power use of the PCs they're in.
SSD is cost effective if your personal use is in line with most users. I couldn't imagine what I'd fill up hundreds of TB with. Save every movie ever made? Download the entire Internet? I have well under a TB of unique data. What exactly do you do that uses so much space?