Kelubar and Shator
Double update to make up for last time's missed one. Behold!
The mid-ranking demodand: contrary to what the picture might make you expect they're still medium in size. Kelubars have reasonable stats, with bonuses from +2 to +10 across the board. Their wings grant them a 60 ft. fly speed, which is quite reasonable, though average maneuverability leaves something to be desired.
In terms of special qualities, kelubars enjoy DR 15/good, immunity to poison, acid, fire, and cold, and SR 25. They also get Evasion and Uncanny Dodge.
Offensively, kelubars have two 1d4 claws (which I presume can wield weapons), and a 1d6 bite. All three of those inflict 1d6 acid damage (1d10 on a crit), and benefit from its 4d6 sneak attack. Kelubars also stink, which can nauseate creatures for a full minute without taking up an action. It's pretty easy to immunize allies to it, too. The 30 ft. range is a bit disappointing, though. Finally, they can summon either 1d2 kelubars or 1d4 farastu, though both of those actions are pretty unlikely.
Finally, kelubars get a number of SLAs, which are moderate at best. The at-will SLAs contain some useful tools, like clairvoyance, detect magic, invisibility and tongues, but the 3/day ones are just pitiful (acid arrow, ray of enfeeblement), and the 2/day ones would be moderately nice if they weren't so limited in uses (dispel magic, acid fog).
In the infinite wisdom of WotC, its advancement table says that kelubars become large-sized starting at... 13 RHD. I'm just going to assume that the default is still medium, but any form of RHD advancement turns you big. Becoming Large has all of its regular perks: more strength, bigger weapons, and slightly more toughness.
Is this critter worth +0 LA? I don't know. 28 strength, +4d6 sneak attack, and Stench are useful, but I don't think it's worth 14 HD. +0 for now, open to arguments for -0.
The biggest and baddest of the demodands: 15 HD and large-sized. Stat bonuses ranging from +4 dex to +10 charisma and +12 strength. Land speed is still just 30 ft., fly speed is 70 ft. but at poor maneuverability. Natural attacks are two 1d6 claws and a 2d6 bite (but weapons are a possible alternative). The natural attacks are slightly more interesting than the other demodands': all three can paralyze on a failed saving throw.
Like the kelubar, this one's got DR 15/good, immunity to poison, acid, cold, and fire, and SR (30, in this case). Additionally, shators are immune to mind-affecting effects. They also got permanent See Invisibility, for what that's worth.
Special attacks are about what you'd expect: ability to summon kelubars, farastus, or (occaisonally) other shators. SLAs that are a very mixed bag, with outclassed offense and useful-but-outclassed utility.
Finally, shators get 8th-level sorcerer casting, which is obviously not all that impressive by ECL 15 but worth noting. I guess you can hit 6th-level spells before capping out, which is something at least.
Ultimately, the package of goodies is enough for me to be comfortable with +1.