I was going to respond with something similar. I don’t have an ER, but have a MH that is being upgraded for better off-road performance right after the first of the year (I wanted more comfort than the ER provides and don’t need the extreme nature of an ER), and could have easily paid cash without stressing finances. 3%-4% money is free when you have a portfolio returning 20%. Heck, I have a second portfolio with more conservative investments throwing off almost 10%.
With that said, it’s a bad idea to finance anything you can’t pay for in cash…IMHO.