But on any route I need to rappel off of I would prefer a twin or maybe a double rope. But generally a twin. I find the twin format easy enough to use on most ice routes I am doing and "safe enough". A double rope will generally add to the safety factor while adding some weight. Many of the better modern ropes will allow you to use them as a twin and a double and in some cases a twin, double and single.
But you need to play close attention to the following on all these ropes.
Falls/ Impact Force/Elongation/Extension
The down side of the skinny twin ropes now available (or at least the pair I have been using for a while now) is they are really skinny and the more common belay plates can be problematic. Too fast on steep rappels for my taste and too stretchy sometimes if loaded as a single rope.
My current twin rope system is a pair of Beal Ice Twins @ 7.7mm and 37g per meter. There are other great ropes and I have used most of them. I just happen to be on Beal at the moment. My first and more than half of them bought at retail fwiw.
I saw a few new ropes at OR this summer. Some of them held great interest for me. Enough interest that I may change a good part of my ice climbing system for some (but not all) projects.
The Edelrid Flycatcher was one @ 6.9mm and 35g per meter. And no question the skinny winner! I comes with a specifically designed belay device...which it needs IMO. All of the ropes mentioned here need extra care on the belays and rappels. More on this rope system specifically coming up shortly.
More here on my take on ropes:
Beal also has the new 7.3mm Gully @ 36gram per meter. Twin and Dbl ratings. Late Jan, 2014 delivery. 36gram per and 7.3mm? Interesting trade off on the already thin and light weight Ice Twin at 38gram per meter and 7.8mm. Another rope I will be using as a comparison to my Ice Twin when I get the chance.
Petzl has a new 7.7mm twin. Sorry unsure what the weight was on the Petzl. I would suspect it is close to the Beals offerings. Mammut has at least one twin @ 42grams per meter.
" Monster Ropes by Metolius are 7.8mm and 38g/m and a double or twin. They are a contender."
I should have more info on all these ropes shortly.
Trango with a 8.1 that is both a twin and a double @ 42grams per meter. They are a very clean set of ropes and available now.
No doubt I missed a few of the new "skinny ropes". But things keeping getting lighter and more fragile...truly "race parts" in gear these days.
Problem is..high performance "race parts" fail in a spectacular fashion. And cost a lot in $ to maintain. Ask anyone who races cars. The twins in particular are not "beginners" ropes IMO. With the current technology I think we are pushing the envelope on ropes. Sometimes, in some places/circumstances bigger and heavier might just be better and much safer. I know it is always cheaper.
I like soloing on ice. Take a look at these ropes yourself. Decide for yourself just how close you are to soloing.
But you really need to check the ratings (Falls/ Impact Force/Elongation/Extension) on all these ropes to see if they are appropriate for your own use. YMMV