The trees are critical, especially vs. burn and Goblin Grenades. The all star of the deck is Snapcaster Mage, who allows you to recast your fog spells. As far as the Jace's Erasure combo, no I haven't tried it. Jace becomes a target as soon as he hits the battlefield. If you don't have any protection for him, he's as good as dead. Devastation tide has also saved me a few times, allowing the recasting of trees that have traded out life, while clearing the field. The key is to be patient and not try to force anything. Ideally I would like to play, turn 1Dream Twist, turn 2 Mind Sculpt, turn 3 Jace's Phantasm (leaving 2 mana to fog or Terrifying Presence), turn 4 Tree, turn 5 any mill card, turn 6 Jace with a fog in hand and then Snapcaster fogs until they are milled out with Jace.
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This deck is really fun to play. I played 30 games with the original build and never once wanted to ultimate Jace, or use the first ability, so I cut the Towers for more Islands. The current build seems good (even though there are 5 Trees in the 75). This deck has it's weaknesses (Goblins) but also makes people want to rage quit with frustration when they can't cause damage. I have had the most success casting Jace turn 6 with a fog in hand for protection. Overall this is a great design, and a blast to play.