I had a similar situation. I went with the 3 PCs with failover. Nothing failed so after a few years I sold 1 and used the other for something else. I regret not buying 1 good machine and setting it up in a way that it can easily be recreated. If you cannot afford any down time then go for the 3. Also those PCs are awesome. Enough room for an m.2 ssd. 3.5ssd and 4 port nic as long as you remove the ssd sled. Make sure to buy the higher watt power supply