aster of B
If it is so, why would you need what details of resistance struts migration would have. With my little knowledge & experience - Sorry for irrelevant comments
on it but if you are looking in a Management perspective [for a case study, may be]- a elegant manager never needs to know about the technology. For a manager [who would have already got the budget and estimates -normally not in his hands] its all about planning of deadlines/milestones and resource utilization and resource fitment/allocation and nothing else. - however, forget this.
Coming back to the technology I do not see any thing that would slow me down [-I never worked on Struts 2
]. Its all about the volume of work and extinct of migration.
When we talk about it
After initial configuration [afterwards its just building blocks]
How many flows do the application have that i need to migrate
Am I going to remove the Form culture and use simple DTO? If yes how many of them are available? How many JSP's are being effected?
Am i going to use the old struts stags or use something new? if yes what is volume?
How many filters do I have? Should i make all of them as interceptors, if possible and applicable?
-validation framework and tiles are more or less the same so no change..
There is simply no challenge, except for volume. I do not know how different is struts 2 file upload from 1.x. In general whatever it is, higher versions would be more easier to live with than the earlier ones