]I have no experience with a Hartco. But for me, the RDL is the way to go. Might be an issue getting one soon though. I was reading today that Shasta Lake is evacuated because of the fire. Hopefully they will be back up and running soon.
Hartco isn't as common, but I've put over 100,000 miles on mine on my Valk standard... They're one of those seat makers where you call 'em up, tell 'em how tall you are, how fat you are, how wide your butt is and they make the seat to match your butt and height...
But I'm open to alternatives...
And sorry, not trying to hijack the awesome ride report thread for a "Which seat should I drop a grand on" thread...

ST 1300 guys only had good things to say about this guy.
http://www.greatdaytoride.com/