I am interested in xenforo and would like to know if there is an option of migration to VB4 along with vbseo, vbdynamics, download manager of vbulletin and wordpress to xenforo without breaking the system and links?
There is a vBulletin 4 importer. There's also methods to redirect vBSEO urls to XenForo.
Regarding your other plugins, I don't know vbdynamics, what does it do? There's an official plugin (Resource Manager) that can act as a Download Manager. You would need a custom importer though to retain your data. There's some Wordpress bridges too but I haven't used those yet.