I ran a [couple][1] of [queries][2] and found the following

    Site | Count of Post Reopened| Count of Closed Posts  |  Percentage of Closed 
         |                       |                        |  posts that are re-opend
    -------------------------------------------------------------------------------
    SO   |        2528           |         69498          |         3.64%
    P.SE |        281            |         3049           |         9.21%


It would seem that since a higher percentage of closed posts got reopened on P.SE than SO I think the opposite is true. You have a better chance of getting a post reopened on a smaller site. 

If you think Moderator vs Community opening is important here's the break down of the #Of voters per reopen. Using [this query][3] 


    Voter  P.SE   SO 
    Count 
    ----- ------ -------
    1      169    861           
    2       18    147         
    3       17     70     
    4        9     70     
    5       68   1380          
    Total  281   2528     

Reopens that involved some moderator intervention was about 75% on P.SE and 45% on SO. If you look at only moderator ones its 60% on p.SE vs 34% on SO.

This means that if your going to get your question reopened on P.SE its more likely to include moderation attention than on SO. I don't know if that's important or not. 

  [1]: https://data.stackexchange.com/stackoverflow/query/62860/post-count-by-history-type
  [2]: https://data.stackexchange.com/programmers/query/62860/post-count-by-history-type
  [3]: https://data.stackexchange.com/stackoverflow/query/62866/re-open-voter-count