Fraxel Dual 1927 Vs 1550?

Great and insightful question. The Fraxel DUAL 1550/1927 is a cutting edge system that uses two lasers which can improve the appearance of your skin. The 1550nm wavelength improves fine lines and scarring, while the 1927nm improves pigmentation. 
The 1550nm penetrates deeper and you would expect more redness and swelling as a result.
As always, an in-person consultation with a board certified dermatologist with cosmetic training is the best way to assess your needs and provide medical advice. 

You will probably have more swelling after the Fraxel 1550 since it does penetrate more deeply than the 1927 but is more effective for stimulating collagen.  There will be redness but not the bronzing of the 1927 and you can apply makeup.  Your skin will feel rough and will start to flake at about 5 days and afterwards will feel very smooth and will glow.  Patients love the result.

As you stated, the 1550 wavelength is a deeper penetrating laser and is more suited for scars, wrinkles, and some mild pigment improvement.  It is non ablative so there is no open wounds.  It will have more swelling than the 1927.  There is some peeling, but more with the 1927.  The 1927 is a "partially ablative" laser that is very superficial and used to help pigmentation and superficial fine lines.  Both laser wavelengths are approved for removing precancerous lesions (actinic keratosis).  In general, I use both lasers at the same sitting, unless someone is only concerned about pigmentation or AK's (1927), or more concerned about scarring (1550).  My video show the 1927 laser.  Also, because the 1550 goes deeper, it is more painful during the procedure.