My 2 cents worth
Having ridden the 2014 four day in Masters at the tail end of the field as rider 217, I can tell you that any special tests, single trail or soft dirt (ie not hard pack) is fu#ked by the time you get to it, first time. Ruts, ruts and more ruts followed by whoops......you get the picture.
Then there is the amount of times you travel over the same piece of ground, by day three the depth of the ruts is amazing, you wouldn't think it possible to get a bike through them. The field might run through a piece of ground 6 or 7 times over the event. You spend your time taking alternate lines to jump over the ruts. Don't get me wrong, its not all doom and gloom, some riding is bound to be great, as it was in 2014. And yes, I could have ridden my Evo enduro bike around the circuit. Though I remember hitting a nasty v-dip on 2 separate days and thinking I'd be in orbit if I was on a vintage bike
Nathan made it in 2014 on his KDX, it would be interesting to get his perspective.
The entry fee is just a small part of the cost to ride a four day..... riding gear, tyres, parts, fuel, yarda yarda yarda. You can trail ride the cross country / sprint series, as a tail end Charlie, for reduced cost, they might offer that?