Exactly so. Provided the pH and hardness are high, adding salt to an aquarium with mollies is not essential, but if you do add salt, the likelihood of any health problems decreases dramatically.
pH 7.2, no salt: X-ray/diamond/blind cave tetras, also gouramis, guppies, platies, swordtails, rainbows
pH 7.5 no salt: guppies, platies, swordtails, rainbows
pH 7.5, a bit of salt: guppies, platies, swordtails, rainbows, orange chromides
Dwarf gouramis, honey gouramis, and chocolate gouramis are really best kept at pH 6.5 to 7.0. Dwarf gouramis especially are 100% likely to be contaminated with a mysterious bacteria that as soon as they get even a little bit stressed they seem to die. Do a search on Google or on these forums and you'll see many reports of this. Basically, I don't recommend anyone keep dwarf gouramis without a quarantine tank and without exactly the right water conditions.
Pearl, moonlight, and blue gouramis are much hardier and will do well at up to pH 7.5 provided salt isn't used. I like pearl gouramis in particular. Blue gouramis (and the yellow morph of the same species) can become aggressive. Presumably this is the males. But otherwise, gouramis are good all-rounders.
If you want to keep the mollies in a brackish water system (arguably the best approach) then you can widen your net to include orange chromides, bumblebee gobies, glassfish, halfbeaks, candy-stripe gobies and a bunch of other cool fish.
Mollies are lovely fish. In a recent magazine article (Practical Fishkeeping, December 2005) I wrote an article called "Five nearly perfect fish", and the number one fish on the list was the black molly. For me, it has everything: it's active, friendly, and quickly settles into an aquarium. It looks handsome in a totally different way to other fish, and healthy black mollies have a velvety darkness that stands out amazingly against green plants (live or fake). Mollies are, of course, relatively easy to breed. The fact that it demands a specific water chemistry is really the only problem with the fish, but if you use the need for high pH and salt as an excuse to keep other salt-loving oddballs, so much the better!
Cheers,
Neale