I've successfully written SR&ED applications myself for businesses certainly less deserving than Tarsnap. We decided the consultants were too expensive and gave it a shot ourselves. One solid week of work for one guy at a company of 10 people netted $30,000, definitely worth the time. All you need is a decent record of work done (I used both github commit log and a bug tracker.)

Unfortunately I expect you'll never get money from a bureaucrat without a little paperwork. Still, you're missing out if you don't even try.