Last one I did was through Ted at Engage. He has always done me right & he really enjoys the business, so I prefer dealing with him.
The experience on the procedure has always been painless, but I have a trust & do the paperwork myself. With this last one I mailed the F4 on 11/20/08 & the can was home on 02/04/09 (WV has been running slow lately due to staffing issues). Typically I've found they run about 6-8 weeks once I send the F4. But... if your dealer doesn't have it in stock, getting it in on an F3 is entirely at the mercy of the manufacturer/re-seller.