I guess the phrase "worth having" is a matter of perspective. To me a used up sub par 340 isn't worth having. I think the mopar R blocks can be had for $1000. For the most part most people just want the notoriety of saying they have a 340. $1000 for 22hp that's .2 in the quarter on the street you will never notice the difference. 340 doesn't have a longer life span when in use.
The 360's make a little less hp per second than a 318 so the difference there isn't as large as what some people would lead you to believe.