Sika T55 is not a very smart solution. Although it is not mentioned when you buy this product I would suggestbthat you take a look at the following URL which provides interesting reading on Sika T55. You will see that it is not a particularly safe product to have your face over for a few hours and I can't believe that this is sold to the public without any warning.
merciaflooring.co.uk/sikat55.pdf(see page 2)
Sika is a polyurethane product as is Mapei 990K and this technology is definately not new. The latest generation of wood flooring adhesives are MS based products which unlike Sika and similar do not contain hazardous substances. I am surprised that you are considering using Polyurethane products which carry warning labels on the containers are difficult to use and generally leave you with a difficult clean up job.