I think ESSM is unlikely. No one has fielded an angled box launcher for it yet, although there is no theoretical reason why they couldn't. But the lack of fire control radar suitable for ESSM is telling.
The linked Focus Taiwan story says it has both HF-II and HF-III, which would explain the two different-sized angled box launchers. Having two AShM types on one ship is relatively rare, especially on one this small. It could be an attempt to diversify the threat to complicate defenses, or it could imply lack of confidence in the reliability or availability of the newer HF-III. I'm betting primarily the latter.
The news story also has a link to a Taiwanese military
fan site (
http://www.mdc.idv.tw/mdc/navy/rocnavy/ch.htm) [I originally thought this was official. My mistake]. That page has a table of characteristics, in Chinese. I've tried to pull out the highlights, with help from Google Translate. My comments are in square brackets:
The class name appears to be Tuo Jiang (Two Rivers)? [Not sure on this]
Displacement: approximately 500 tons
Dimensions: Length 60.4 m, Width 14 m, Depth 6m [Hull depth or air draft, possibly?], maximum draft 2.3m
Propulsion: 4 diesel engines, 4 waterjets
Speed: 38 knots
Endurance: 2000 nm [no speed given]
Crew: 34
Sensors: 1 air search radar, 1 gun fire control radar, electronic warfare equipment
Armament: 1 x Mk 75 76m gun [Evidently not a Super Rapid, despite the stealth cupola], up to 16 x Hsiung Feng antiship missiles [mix of 8 HF-II and 8 HF-III appears to be standard], 1 x Phalanx CIWS, 4 x 12.7mm machineguns
Dates: prototype contruction began 11 November, 2012; launch date March 14, 2014 [estimated]; completion date November 4, 2014 [estimated]; no delivery date set