DisableNewProfilesBeta.user.js

// ==UserScript==
// @name         Disable New Profiles
// @namespace    http://tampermonkey.net/
// @version      0.7.5
// @description  Modifies all profile links to bring you to the overview page. Also fixes overflow issue on new profile page.
// @author       /u/corylulu
// @match        https://www.reddit.com/*
// @grant        none
// @require      https://code.jquery.com/jquery.min.js
// @require      https://raw.githubusercontent.com/uzairfarooq/arrive/master/minified/arrive.min.js
// @run-at       document-start
// ==/UserScript==

(function() {
    'use strict';
    function modifyLink(a){
        var href = a.attr('href');
        if(href) {
            if(href.match(/\/u\/[^\/?]+$/) || href.match(/\/user\/[^\/?]+$/))
                a.attr('href', href + "/overview");
            else if (href.match(/\/u\/[^\/?]+\/$/) || href.match(/\/user\/[^\/?]+\/$/))
                a.attr('href', href + "overview");
        }
    }

    $(function() {
        // Modifies all existing links
        $('a').each(function(){ modifyLink($(this)); });
        // Modifies links dynamically added to page
        $(document).arrive('a', function() { modifyLink($(this)); });
        // Fixes overflow issue on new profile page.
        var p = $('.ProfileTemplate__content');
        if(p)
            p.css("overflow", "auto");
    });
})();