AJAX/JQuery/Memcached Chat Engine to XMPP/COMET/BOSH chat engine

I have social media website, where users login and chat with each other, it was originally built with a AJAX/JQuery and MYSQL as the backend with the select and inserts, but when the number of users grows, i had to redesign this without the MySQL to just to select from the Memcached only. And dump the data to the DB periodically, Now the issues is site has grown more now even the memcached is not enough, So i need some kind of a proper chat technology like BOSH or COMET, to based my chat engine, since the original script is written in Jquery i think its can be one of the following (but not limited too...) ejabberd XMPP server with BOSH Strophe JavaScript XMPP library jQuery JavaScript utilities Apache web server as BOSH proxy Requirements are 1. I need to store chat messages into a mysql table (periodical dump) 2. I need design of the chat engine to be same as of now, but enhance few things like opening tabs instead of windows for multiple chats, ability to send emotions ... etc. 3. Needs to be able to handle the simultaneous users around 1000, without a problem. 4. Only gold members are allowed chat, so this contraints needs to be there, plus not hackable via other non-gold members is a must. 5. Website is script is based on able-dating script but its heavily customised by me so...and its 100% open. I need to know 1. How much ? 2. How long ?