What kind of Riptides was he running? Because Riptides from the standard Tau codex do not have any haywire weaponry at all. I don't know if he was running a Forgeworld variant or from the Farsight Supplement, as I have none of those, perhaps someone who plays Tau more can inform me on this...
As for the Multi-melta, yes you would only be able to snap-fire it as Deepstriking counts as moving at-least combat speed for it's occupants, and since a Multi-Melta is a Heavy weapon, you'd have to not move to fire it normally.
: 5 Storm-teks is 125 points. The only thing they lack is a reliable delivery service. So one could be replaced with a Harbinger of Despair with the Veil of Darkness for Deepstriking, or attach Obyron to the unit.