They're absolutely fantastic on vintage bikes. They're all I'll use on my 1983 GS850G.
No idea about using them on a DL, but they are modern, high-quality tires. Bias-ply, although that makes less difference than many think it does.
You're certainly not going to save any money over a pair of quality street-oriented radials (for example, the Bridgestone Battle Wings) in the correct sizes, so I'm not sure I see the point.
There are some über-cheap DL riders who have been happily using 100/90-19 Shinko street tires in order to save a few bucks.
2002 Suzuki DL1000 V-Strom, Dark Metallic Space Blue
1983 Suzuki GS850G, Cosmic Blue
2005 KLR685, Aztec Red - Turd II.2, the ReReTurdening