Hi Pierre

Lots of good advice ( if somewhat differing) here.

However I will offer this - I have used 12 strings guitars for many years.

I use it as a second instrument to six stringer for certain numbers.

With regard to tuning I had no problem -; being able to tune by ear on my six stinger. Of course it takes a little longer because you have twice as many strings.

What I did when I got my first 12 stringer was to tune it using the thicker set to my standard set up six.

Then I tuned in the thinner ones by ear. At first I did have problems getting it dead right as I found that my 12 stringer did not hold it's tune as well as the six. But practice soon got my around this and I have had three others and have had no problems.

I use light strings and standard tunings and have had no problems with neck or body etc.

I will say however that you should try to learn to tune by ear as it not only is the best way to ensure perfect pitch but I found it helped my music generally as you are more aware of the tonic qualities of the music.

Whatever you decide I am sure that you will enjoy the experience of playing 12 strings but I agree with others above that you should treat your six and 12s as completely different instruments. There are many things I can do with a six that I have difficulty with on the 12 and vice versa.

Happy Playing and let us know how you go.

regards

Mike