Dodgy,
4.5 months is a long time compared to some tales here... Don't make it any easier though...
Yes, the mediation route is far and away the best to take if you can get him to play ball.
Take advantage of Wikivorce and save yourself as much time with your solicitor as possible - thre is a lot of knowledge and experience here.
He too needs to stop and think a bit here. Throw 8-12K EACH at solicitors, or sit down around a table and be sensible? Tough call, but as the old experession goes - 'you can lead a horse to water, stick its nose in, jump up nad down on it's head, but if it isn't thirsty, it won't drink.'
He needs to hear it from someone independant, rather than his own solicitor, who will only benefit from making the proceedings drag out.
Why not see if you can make a mediation appointment for both of you?
Have a read at this thread (click on the link below)
http://www.wikivorce.com/divorce/Divorce-Forum/Mediation/3393-Anyone-been-through-mediation.htmlMike