I don't mind you not using quieter or quietest, but I do mind you telling me, a native speaker of English, that these forms are incorrect. I don't mind there being exceptions to the rules. I meant shorter adjectives as in the sense shorter number of syllables. I believe that the forms like more quiet (1.01 m ghits), most quiet (250 k ghits), securer (204 k ghits), securest (164 k ghits), just show that the system is in a state of flux. (Quieter (14.5 m ghits), quietest (2.86 k ghits), more secure (30.3 m ghits), most secure (5.67 m ghits).) More sure may be preferred by speakers because of sure ending in an r sound. Fun may be problematic because both fun and funny are adjectives.

Also, I do like the comparison of adjectives in -ly.

A goodlier sum of money I have never seen.

Ceci n'est pas un seing.