It’s my experience that that’s usually short-sighted. It’s often prudent to not upgrade to the “.0” version when you’re already making a project, but once “.1” rolls around of the new version, it’s time to update. If you don’t, you will run into known bugs, and you won’t be able to fix them because they’re already fixed in newer versions. And, finally, you’ll realize you HAVE to update – two days before hard freeze. Better pay it at a time you can control, and not have to worry about those bugs at all during development.
29 times out of 30, a content pack will work just fine with a newer version of the engine.
To add it to a project, click “add to project,” then in the add dialog box, check the “show all projects” checkbox, choose your (newer) project, and then select the latest available version number to actually add.
Once it’s added, open it up in the engine, and it should work fine.
Once in a blue moon, some required blueprint functions have changed, and you’ll have to re-wire some missing nodes. This is similar to the kinds of things that CAN happen when upgrading project between versions. As long as you’re methodical about it, it’s really quite easy, and well worth the effort.