I'm replacing my old beat up 10.5mm rope; planning on getting one or two new 60mm lines. I climb mostly long trad routes, but also sport, some alpine, and walls. I'm mostly concerned with a good way of bringing along a second rope for rappels, but also need the ropes I own to accomodate jugging and hauling. I prefer leading hard trad on a single rope, but certainly appreciate the flexibility of doubles for traversing pitches.

Options I'm considering:
1) Set of doubles
2) Single plus a static 8mm tag line
3) Single plus a dynamic double
4) Other?

Some questions:
1) I've never rapped on an EDK with two ropes of different diameter. Any concerns with this, other than the small one feeding faster?
2) All the double/half rope manufacturers seem to recommend using a pair of the exact same rope. Is this a real issue? Any problems with leading on a single/double combo (treating them as double ropes)?
3) Anyone jug and/or haul with a static 8mm line? I'm a little concerned about durability on big walls.
4) Other issues?

Thanks in advance for feedback and thoughts.

-Woody

Question #1:
When I thread the anchor, I thread the fatter rope and tie the EDK. Otherwise, when the skinnner rope feeds through your belay device faster, it moves the knot away from the anchor, making the ends uneven. I noticed this when my partner was rapping over uneven terrain, and had to keep bouncing on the rope. The knot moved about 8 feet away from the anchor. But on a near vertical rap, it only moved a few inches.

But it sure sucks pulling the skinner rope, so we only threaded the fatter one on long raps.

70m edelweiss used by a 195 pound guy who takes large whippers and does new routes will last about two seasons. Go figure.

A few points here were discussed recently in this thread.

Sounds like from your desired use that doubles will not be the way to go. If it were me I would go with a single 10mm Sterling or Mammut for durability. Both seem to be able to take a bunch of abuse which you will give your rope if jugging. As for the second rope, a single 8mm static will handle hauling on some small walls, but will get thrashed pretty quick on El Cap. I have had good success with 9mm Mammut static ropes for hauling though.

If you want a second rope to use on longer free routes for bailing/descending an 8mm static will work great and last a long time. It also allows you to alternate the knot when doing multiple rappels(pull each rope on successive rappels). I will usually back up my EDK with a single overhand on the trail line snugged up below the knot which over doubles the strength of the knot(actually increases the force needed to have the knot roll).

I have used tag lines down to 6mm with some success, although then you will want to always have the knot on the tag line side. Pulling a 6mm rope for 5 or more rappels gets old quick. With a 7mm you can get away with alternating the knot IF you use an autoblock. The autoblock keeps one rope from feeding faster through your device and keeps the knot from creeping down as you rap.

A couple of things on using a 6 or 7mm tag line, always add 5 meters to the length of the tag line over your lead line. The static will not stretch and can get you in trouble if both ropes are the same length. Also use a blocking knot with these smaller ropes, which is basically a EDK with an extra twist. I always back it up with an overhand below the knot on the tag line.