I found this article on the National Center for Biotechnical Information website about jump serving. The study was conducted by the National Institute of Physical Education of Catalonia, Barcelona, Spain.
A comparative study between serve mode and speed and its effectiveness in a high-level volleyball tournament.
This study carries out a comparative analysis between serve mode and
speed and its effectiveness at the 2004 Men’s Olympic Qualification
Tournament. METHODS: A total of 377 serves were analysed, 124 of which
belonged to Cuba vs Holland, 63 to Spain vs Cameroon, 100 to Spain vs
Cuba, and 91 to Holland vs Cameroon. Serve were recorded using a tripod
mounted radar gun. RESULTS: The analysis has shown the predominance of
jump serve (JUMP, 84.9%) compared with float serve with jump (FLOAT
JUMP, 5.6%) and float serve (FLOAT, 9.5%). Only 25.3% of the total jump
serves analysed was successfully stricken back making the first tempo
attack possible. The respective percentages for FLOAT JUMP and FLOAT
were 42.9% and 55.6%. Ball speed in JUMP (23.03+/-3.94 m.s(-1)) was
markedly higher compared with FLOAT JUMP and FLOAT (12.05+/-3.44
m.s(-1) and 11.47+/-4.22 m.s(-1)). While negative outcomes (66.7%) in
FLOAT stand out, a better balance between negative and positive
outcomes were found in both JUMP (50%) and FLOAT JUMP (42.9%).
However, no relationship was found between serve speed and its effectiveness outcome (R2=0 in the overall sample and R2=0.005, when pooling the five serve effectiveness categories into negative and positive outcomes. In fact, JUMP was mainly performed in the span of velocities between 23.06 and 28.06 m.s(-1) in both error and direct point categories.
CONCLUSION: We found no significant relationship between serve velocity
and a better outcome related to effectiveness. In addition, JUMP and
FLOAT JUMP present a better balance between negative and positive
outcomes compared with FLOAT. http://www.ncbi.nlm.nih.gov/pubmed/18212707
My take on this is that the Jump Spin serve is the most effective in taking the opponent out of their offense. In addition, it is not the velocity of the Jump Spin serve as much as it is the location that makes the Jump Spin serve effective.
It seems as if in the men’s game, the obvious choice is to jump serve. Anyone have any data on the women? Should the women be Jump Spin serving more?