On to the Heavy Support slots. There are a lot of these, and mostly they are good choices. Mostly...
I loves me some dark reapers! The bane of smurfs near and far! They finally got an armor upgrade in the 4th edition codex (a fact most people seem to have overlooked), and their exarchs have access to some mean and nasty options. The only change I would recommend is giving the exarch access to the Dire Avenger exarch Bladestorm ability.
HA HA HA! No, I'm kidding. That would be way over the top. No changes.
BS 3 sucks. Make it BS 4 like the Fire Prism and Night Spinner OR upgrade the pulse laser to something scary, like S9 Lance. OR hey what about letting us use them in squadrons? I have five falcons. I never use them. 'Nuff said.
The favored child. A higher BS than the Falcon with a blast weapon carrying two optional firing modes AND the ability to link up with another Fire Prism for +1 to Strength and AP. It also has a greater range than any of the other Eldar weapons. I'm tempted to ask for the ability to run these in squadrons, but my inner sense of game balance says no.
I really like the Night Spinner. The Doomweaver is a fun, interesting weapon and above all it is different. I have three Fire Prisms that have been magnetized so that I can run them with as prisms OR spinners.
Earlier this year I ran three Night Spinners in a tournament, hoping to use them to blob up big sections of the board and slow down approaching enemies; it didn't go so well. Without being able to run these in squadrons, there's no way to cover enough of the board to bog down a massive attack force. That being said, I wouldn't change anything! Bringing one of these is a big win!
Support Weapon Battery
... these things really suck. Two guardians attached to a semi-mobile gun platform whose weapons seem more problematic for the Eldar than their enemies.
D-cannons are wonderful, but their short range, lousy BS and thus their scatter ability make them hazardous to use. BS 4 please, or the ability to twin-link their shots when run in units of more than 1.
Vibrocannons I just, I uh ... I just don't know what to do with these. They are a goofy weapon, and like the Doomweaver they are different and thus fun. No changes!
The Shadow Weaver profile should simply change to match that of the Doomweaver, small blast or large.
War Walker Squadrons
Other than dropping wraithsight, no changes.