revised.js

if( Meteor.isClient ){

var step = function(e, direction) {
    var toStep;
    
    e.shiftKey ? toStep = 10 : toStep = 1;

    if(direction === 'down') {
      toStep = toStep * -1;
    }

    return validValue.call(this, Number(this.value) + toStep);
  };

  var validValue = function(val) {
    if(val >= 100){
      return val = 100;
    }else if(val <= 0){
      return val = 0;
    }
    
    return val;
  };

  Template.input.created = function() {
    this.data.valueDep = new Deps.Dependency();
  };

Template.input.helpers({
    value: function(){
      UI._templateInstance().data.valueDep.depend();
      return UI._templateInstance().data.value;

    }
});

/*
  Template.input.rendered = function() {
    var _this  = this,
        $input = $('input[type="text"]'); //
    // Set up a Deps on the input's value
    Deps.autorun(function() {
      if($input.is(':focus')) {
        var selectionStart  = $input[0].selectionStart,
            selectionEnd    = $input[0].selectionEnd;

        $input.val(_this.value);

        // Reset (i.e. don't move) the cursor position
        $input[0].setSelectionRange(selectionStart, selectionEnd);
      } else {
        $input.val(_this.value);
      }
    });
  };

*/
  Template.input.events({
    'keydown input' : function(e) {
    
      e.preventDefault();
      var that = this; //preserving context for input binding
      
      switch ( e.which ) {
        // up arrow
        case 38:
          that.value = step.call(that, e, 'up');
          that.valueDep.changed();
          break;
        // down arrow
        case 40:
          that.value = step.call(that, e, 'down');
          that.valueDep.changed();
          break;
          
      }
    }

  });
}