I think there are two basic areas that need to be considered when comparing and contrasting stainless steel versus titanium watches.
On the one hand, you have your performance considerations; and in this regard, most factors tend to favor titanium. It's noticeably lighter than steel, and for all intents and purposes, it's absolutely corrosion proof. It is fair, however, to ask just how significant these performance advantages really are. After all, the case of a well maintained, high quality stainless steel watch will provide several lifetimes of reliable service without developing any serious corrosion problems. Likewise, as we know from our blade discussions, steel is stronger than titanium (when comparing material of equal thickness). So, although I would tend to give the edge here to titanium, I think that, across the board, the differences are pretty small. IMHO, the weight advantage of titanium is the only of these factors that I would consider to be significant.
Alternatively, there are also aesthetic differences between steel and titanium that need to be considered. Though this is a much more subjective topic, I tend to give stainless steel the advantage here. With stainless steel watches, the manufacturer has, at a minimum, the option of brushing, polishing or bead blasting the case. Each individual treatment gives the watch a unique look and feel. Most titanium watches I run across, however, seem to favor something of a brushed finish. In this form titanium appears a bit flat and dull, and seems to lack much of the luster present in stainless steel. Being softer than a quality stainless steel watch, a titanium case is also more prone to getting scratched up.
Not suffering from any carpal tunnel related problems, I kind of like watches with a bit more heft to them. So for me the decision to stick with primarily stainless steel is an easy one. But I certainly wouldn't dissuade anyone from purchasing a titanium watch that appeals to them.