Hijust to share some of my experience and see what you decide to do I have worked on a project which the end result is packed into a jar (actions and stuff)and will be throw into and coexist with other project. To run the project, I simply put the jar and related jsp and struts setting xml's into another project and everything will run. I have deployed my project into 2-3 different projects(all using plain servlets) in my company and . And all worked fine, meaning no major compatibility issues. Except for one, I have the performance issues described on most places you have seen. And I basically did the same thing as what they all did, I changed Struts tags to JSTL tags, and everything just worked fine.
All I can say is that from my observation its probably the different jars files included that my cause some conflicts. I have not have the time fully test it out. so just something to share with you.
