In 2011 I did Loch Ness in 3:15:00, then 4 weeks later did Dublin in 3:12:27. Dublin is a more generic profile so it easier to pace yourself, whereas as Loch Ness has so many steep downhills and long climbs that it's difficult to know how fast to run in the first half. You CAN always them both; 4 weeks is long enough to recover for another flat out effort.
Used similar apps for Brighton and Paris marathon's. Both were good and would use either again. Best things about them are how they send out notifications to friends/ family at certain check points, and display your location on a course map.
Does the pain persist long after your runs? is the burning on the inside or outside part of your shin? You might want to google exertional compartment syndrome if the pain is on the outside, and is relieved shortly after you stop running.
So they've made the 18 - 39 time a bit tougher I see. Fair enough; 3:10 was a bit of a soft target but they probably could've given people more notice. Still, I suppose they'll fill the race easily anyway so can do what they want!