Hey dude
Pesonnaly ive used both.... i find the 25mm rope easy to construct and maintain. although the weight of them is not as nice
12.5mm rope twisted one way and then twisted togethe so it locks on itself IMO makes the best ropes - because the knot you tie on the end gives a great wieght.
Basically way up the time you want to spend making and the cost mate.
12.5mm you will need double the lenght and more time to build.
25mm half the length and not time at all.
Burn time is about the same.
I must say tho that my tied 12.5mm ropes have lasted longer and feel more robust.
Hope some of it helps - post us some pix when youve made them dude it will be interesting to see how you go about it.
