SONAR x1 LE migrate to steam to eventually get the Professional? is this even logical?

Right now its the last day of the steam sale and it appears that buying the steam version of SONAR and then immediately upgrading to the professional is the same price as simply upgrading to professional form x1 LE, however I am a steam user and find the package deals on steam and sales etc. to consistently undercut the regular deals. FOr example there is the instrument upgrades pack that bundles 20 or so $20 special instruments for a $160....but as an x1 LE user I cant buy it as you have to be a steam sonar user.
 
Are there any nown issues attmpting to keep my music files from regular LE and migrating to steam?