Allan, all my customers have the option of upgrading to the 300gpd for very little cost, but very few have seen the need. Quite a few ask about the upgrade when ordering, and I tell them there is no need. I then tell them should they find that they are not producing enough then the upgrade is still available as and when they need it, I have had only a handful of people upgraded. Remember that most of these people use a storage tank of some sort.
I know exactly what you mean about speed and good results, but it depends more on how you use the water, as opposed to the volume of water you can go through in a day. Like I have said in many posts on this forum, I have seen lots of people, wasting lots of water, and lots of time.
Peter