I have an 138 and one L1200 (that I havn't used yet) and one Durst M70. Since I don't plan on enlarging anything larger than 4x5 at the moment, the 138 goes up to the attic. And since the L1200 seems to be able to deal with 35mm really well, compared to the 138, the M70 will stay in the attic as well. Actually, I only have space for one enlarger in the darkroom...
The spring on my 138 is more like a wire that helps holding the head up. I didn't have any problem dismounting it and transporting it in my Volvo V40.