A one gallon is just fine and safe to heat.. and a 1-4 gallon tank, filtered and non filtered, takes the same amount of cleaning..
The only difference is how much room there is.
I agree with you, but not completely. I still believe that 1 gallon is still not really enough for the betta itself. Yes it has room to swim and live but really is it comfortable?...
Before I joined the forum I remember thinking that 1 gallon would be fine, but was told that bettas in fact need at least 2 gallons.
Now people are spreading around that 1 gallon is fine, but really it isn't. Yes there are so many opinions on this, but I stand by the 2 gallon minimum unless you are breeding because breeding and jarring fry can really be expensive if you want to have a ton of 2 gallons for each of them.
And a 1-4 gallon tank does not take the same amount of cleaning unless there is only one fish in both and it still depends. It mostly depends on how many fish you have and any other kinds of creatures in there that are able to procure waste.
--------------------------------------
I have to admit that I have been wanting that tank for so long. Just haven't been able to find it.. It looks custom made though. Either way it looks amazing.