I have an idea for this.

Add a new plugin event 'beforePublicPage' 'type'=> ... and some information
(using it for beforeSurveyPage too)

Use this event to do a new plugin :
'beforePublicPage'
type=> 'surveylist'

if(App()-getQuery('sid'))
redirect to survey

Deactivate dby default,

name it 'oldUrlCompat'

\o/ i think we can do it without a new event :)

Got it : limesurvey.sondages.pro/index.php?sid=714997

Make the pull request and the plugin today

public function afterPluginLoad()
{
    $oEvent=$this->getEvent();
    $sControllerId=App()->getController()->getId();
    $iSurveyID=App()->request->getQuery('sid');
    if($sControllerId==="surveys" && $iSurveyID)
    {
        // TODO: Redo the $_GET params
        $url=$this->api->createUrl('survey/index', array('sid' => $iSurveyID));
        App()->request->redirect($url);
    }
}

Need to reconstruct the GET parameters (for enterUrl)

Plugin is here : https://github.com/LimeSurvey/LimeSurvey/pull/424
Actaully ion cpore, but can be put in plugins temporary

I tested the plugin and while it works with the plugin, the new style URLS no longer work, and the link from the survey details no longer works (since it is a new style link)

@lowprofile : with GET or PATH ?

I test with PATH : seems to have no issue. ANd in teory : it must work with any url. We do something only if controller is surveys (survey listing)

@lowprofile :can not reproduce:

path:
newurl : http://testing.sondages.pro/limesurvey/index.php/10000?newtest=Y
oldurl : http://testing.sondages.pro/limesurvey/index.php?sid=10000&newtest=Y

get:
newurl : http://testing.sondages.pro/limesurveyget/index.php?r=survey/index&sid=10000&newtest=Y
oldurl : http://testing.sondages.pro/limesurveyget/index.php?sid=10000&newtest=Y

@lowprofile : waiting for you feedback : find the way to broke this.

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=17053

2.5+ Build 160202 released