I also brew partial mash starting with liquid malt extract, most of the time at least. I have brewed dozens of batches.
The only significant drawback that I am able to ascertain is that, when brewing a beer that is supposed to be pale, there is greater carmelization of the wort in the brew pot due to the higher concentration of sugars, leading to a somewhat darker appearance than one might want for a pale beer.
It does depend on the water you have available however. I happen to have a private well so I have a source of chlorine-free, sanitary, cold water. If you have city water then you might want to take steps to get the chlorine out of it, or you'll end up with chlorophenols which adversely affect the aroma.
With a full-mash boil you not only need a bigger pot, you need a larger heat source. Ideally that's a freestanding burner used outside, although if you can place the pot across two burners on a kitchen stove that can be made to work too. Also, you then need a wort chiller.