I used Kenda 270 knobbies on my KLR. TKC 80's were very good for compromise on/off road but
wear very quick.
Not sure that I would run TKC's on the Vara due to the wear factor (+ heavy Varadero)
The Heidenau's sound like a good compromise for both road and modest gravel and FSR (forest service road) ....I've been using Anakee 3 and don't have much confidence on rough/loose gravel or FSR's ...good offroad (dry) is ok, but...
I've seen a few KTM Adventure fitted with Heidenaus and the owners are quite happy but I've read some comments about sidewalls popping ...probably when really pushing it offroad ...check ADV rider forums
I don't know about mixing Front & Rear but I ran TKC front & rear on the KLR no problem ...as you probably =know by now the VAra is a big beast as soon as you get off-road and,
personally, I find it a handful so I tend to stay on "good" off-road ...it doesn't like wet/mud
You need to decide what you will be riding ....lots of off-road (=TKC'c) ...if you need to ride on road to get there ...then probably something like the Heidenaus ...occasional off-road adventures on good (dry) trails = Anakee 3 (or similar)
I'm tempted to try the Heidenaus (front & rear)
Let us know what you try...
Anyone tried the Kenda Big Block? ...probably cheap and fast wearing (..and noisy on road) ...
but digs into the dirt