Sagging does occur w/heavy items. My line is at 2nd story height so it is not a problem. I have king size bedding and can put it ALL on the line the line at once. The metal line can hold a lot of weight, many pairs of jeans are ok.
The Lehman kit comes with a ratcheting tightener so as the line stretches over time you can tighten it easily.
The clothesline spacer can help w/sagging. You hook it onto the line when you've got it half loaded & it rolls along the line on pulleys. I put a clothespin on either side of it so it won't run into the clothes as it moves. The "pinching" effect cuts the sag in half. If you had really heavy stuff I suppose that you could use two. My line is 75 ft. long, the kit is 50 ft. http://lehmans.com/shopping/product/...ProductID=2719
I bought mine before they offered the kit, and it was a lot more $. I did get the larger pulleys and heavy duty line...the kit comes w/the smaller pulleys and a lighter line b/c it's relatively short.
For the installation it's very important to have heavy duty screws, hooks, etc. A load of king size bedding sure can flap around in a stiff breeze!
I want a second line for the days when it has rained for a while and I want to do a LOT of laundry when we finally get a sunny day.
I got a cheapie "umbrella" dryer for smaller stuff. Got it at Meijer, they go on sales several times a year. It rotates so you could put it next to a patio for a dry place to stand while you hang stuff. I don't use mine much any more b/c the vinyl coated lines sag a lot and got funky black stuff on them...probably should have brought it in for the winter. Someday I find someone willing to replace the line for me...hopefully my dad when he visits next week, we always need to find a project for him to work on!
Lehmans also has an assortment of indoor drying racks. They are pricey but should last forever if used indoors.
HTH and happy line drying!