Should I avoid using Reactive-Var using this approach?

This simple Messaging App is created to demo the following concept. Suppose I would like to display total number of messages I had with other users, by temporary saving the result of findOne() in the helpers function into “this.varName” and retrieve it at the template with {{varName}} as shown below.

I am aware that Reactive-Var package is more powerful except the varName is retrieve with {{instance.varName.get}}, and it required another install of the package. For my simple usage I think my approach is good enough. But is that a bad practice? If it’s not please advice better approach. Thanks.

<template name="chatTemp">
   My total Messages with
   {{#each users}}
      {{#if notMe}}
         {{#if hasMessages}} {{totalMessages}}
         {{/else}} 0

/* chat.js

   User document schema : { _id:string, username: string }

   Chat document schema : { _id:string, 
                            user1Id: string, 
                            user2Id: string,
                            messages: [string, string,...] }
Chats = new Meteor.collection('chats');
if (isClient) {
      users: function() { return Meteor.users.find(); },
      notMe: function() { return Meteor.userId() !== _id; },
      hasMessages: function() {
         var myId = Meteor.userId();
         var otherId = _id;
         var chat = Chats.findOne({$or: [{user1Id: myId}, {user2Id: otherId}]});
         if (chat && chat.hasOwnProperty('messages')) {
            // *** save result to "this" (i.e. user document), bad practice?
            this.totalMessages = chat.messages.length;
            return true;
         return false;