Outside of exceptions, I don't think free agency will be where the Raptors make their big splash. I could be wrong but that TPE from Barbosa is useless if the Raptors wait for free agency.
To put it in perspective, in looking at additions to the roster for next season, as things stand now the Raptors have $13.5M to spend ($11M plus $2.5M top up exception) in free agency versus adding up to $18.6M via trades ($11M plus $7.6M) and then another nearly $7M via exceptions ($5M MLE, $1.8M Bi-annual).
So considering free agency usually almost always ends up in over paying for talent (with this year being even a greater risk considering the number of teams with cap room), which would you rather?
$13.5M via straight free agency
or $25.6M via trades and exceptions.
(*Don't forget minimum contracts can be added once a team is above and beyond the salary cap. A lot people have been talking about trading the picks, myself included, but some seniors coming out of the NCAA could be interesting picks in the 2nd round. Seniors aren't necessarily going to step in right away - right, Adam Morrison? - but they would be less of a project and help to cheaply fill out the roster and maybe they get that elusive diamond in the rough).
And important to note that I believe this exceptions will not exist if no trade/use of TPE happens prior to July 1, so I definitely go for the trade route.