It's good to have a mix of
NFWs in your units, especially some swords as the 4++ is pretty useful against other Termies and
MCs.
GK Terminators have been taking a hard beating since there's so much AP1/2 flying about these days. A unit of Eldar Guardians can effectively wipe a Termie squad, with their psuedo-rending. Flying
DPs will get the assault on you, and just wipe a whole unit in one go. Intercepting Riptide will kill your DSing units before they even have a chance to do anything.
Dev Cents will ruin your
You should buy 10-man units with 2 Psycannons each, and then combat squad the units, putting both psycans into one group. This will allow your psycans to target the heavy armour, and the
SBs to gak infantry. Much more effective than wasting whole units of shooting to get one psycan to shoot a Dread or Wraithknight (ie. targets that bolters can't even scratch).
How are you planning on delivering these guys to the battlefield? Walking Termies is a terrible idea. On boards where you can rely on terrain, your units will be super-slow. On boards where they can move freely, there's no cover to rely on when that Crisis Plasma Team nails you.
The core of any good
GK list (not Henchmen) is two
GKSS. They will have max psycans, and Psybolts if you can afford it. Preferably, they will be
TL by an Inquisitor.
The other fantastic units in the codex are the Dreadknight (which you've already figured out), the Psyfleman: 2xTLAC with Psybolts for 135pts, and the Vindicare. While these are all expensive, single-model units, they are all worth the cost. Take an
ADL to get some cover saves, too.
The H.psycan on the DKnight is pretty terrible compared to his other options. Consider a Teleporter and an Incinerator, and that's it. Or, to save even more points (although it will make him less effective), skip the teleport and
DS him into play. He'll not assault till T3 (instead of T2 with the teleport), but he won't get shot T1.