Well....

Keep in mind that everyone has an "expected" or "acceptable" level of performance.
When you add weight (yeah the higher the mAh the more the weight), then the
performance is typically reduced. So, if you want to do stunts and things, then you
might want to be careful about how much weight you add. On the other hand, if
you just want nice easy cruising, then you can get away with adding more weight.
Sure, the quad will NOT be as responsive, however, the fly time might be extended.
That said, there is still a point of diminishing returns where the weight becomes more
than the drive train (motors and props) can handle. 

From what I can tell, manufacturers seen to strive for a good middle ground; something
that will give good performance and still a half decent fly time.

My standard battery is a GNB 3S 1100 mAh 67 gram battery which I use on everything
from 2.5 inch to 5 inch quads. It is a bit heavy on the 2.5 inch, but I get over 15 minutes
of fly time. The battery is almost a bit light for the larger quads, but I still get about 10
minutes even on 4 inch and 5 inch quads. These larger quads are used for high altitude
{over 350 feet} easy cruising. 

When I want to play around, then I will use a 3S 650 mAh battery on a 2.5 inch quad. 
Yeah, it doesn't fly as long, but it is much more agile and will do flips, spins, and rolls, just fine.

Just keep in mind that the manufacturer's battery recommendation is likely a middle ground
and a very good starting point. If you like it, fine. If you don't, then move up or down a bit.

I use a 1S 550 GNB HV and get around 7 minutes at 4k feet above sea level at fast enough speeds that I can't see the gates well due to the low camera angle. I didn't want to use the connector it came with either so I did solder on a PH 2.0 even though the connector it came with is said to be better and is rumored to improve flight time. I love 1S drones so I have a fat stack of PH 2.0 batteries already. After sorting out the ESC firmware issue this thing has quickly become my favorite 1S drone.

Hi Vaeloron,

What quad are you running?? How many??

Since your 1S battery is a GNC, I am assuming that it came with a GNB27 connector (black).
I have not used batteries with the GNB27, however, I have many BetaFPV 1S LiPo batteries
with the BT 2.0 connector. I will say that they are absolutely better than the PH 2.0 connectors.
The current draw is much better. I only have one quad, the BetaFPV Meteor65S that uses 
the BT 2.0 connector, but I can tell quite a difference  in the batteries. 

From what I have researched, they say that an XT30 is even better, but I think that is overkill
on a 1S...maybe. I believe the BT 2.0 to be fine.

I also use the BT 2.0 connector for connecting certain components in my larger builds as well.
I like it MUCH BETTER than the PH 2.0 or PH 1.25 connectors. Specifically, I always use a
connector on the power leads to the GPS unit so that it can be powered without the need
to power the quad.