Good question, AJM.
Here are some biased thoughts:
Having used both I'd say that (all else being equal) the Ti stove pumps out the heat a little quicker on start-up than does a steel stove. Likely this is due to the thinner wall and top thicknesses on the ti stove, and not due to the type of metal.
Once you have a steady fire burning, and you keep it burning steadily rather than allowing it to wax and wane (like my absent-mindedness usually does), the difference in output between steel and Ti same-sized stoves is negligible.
The especially thin-walled Ti stoves will release their heat more immediately than steel, and retain less heat between burns. Again, this is likely because of the metal thickness, and not type.
Weight is a big consideration, but for me, corrosion is as big a consideration as weight. Apart from the inevitable steel parts on the Ti stove, titanium just does not corrode whereas the steel stove always has a little rusting going on no matter how careful I am when drying it and storing it.
I expect I'll keep using this (1998 version 4-dog) Ti stove for another 20 years, then pass it on to my son and he'll get another lifetime out of it. I know the steel stove will not last that long.