Firstly, this is the variation of the Theta class shuttle that I use, it is different from the one in Way of D'era, due to its size. The evidence from DS9 suggestes the ship is similar in size to a runabout, while Way of D'era puts it closer to the Defiant...
Main: Class 2 (+1 Bonus) - 1 power/round (2 SU)
Backups: 1 (1 SU)
Inetial Damping Field
Main (12 SU)
Strength 8 - 3 power/round
Number 2
Backup (3 SU)
Strength 5 - 2 power/round
Number 2
Attitude Control - 1 power/round (1 SU)
Communication Systems
Type: Personnel - 5 power/use (16 SU)
Pads: 4
Emitter/Receiver Array: Personnel Type 6 (40,000 km range)
Energizing/Transition Coils: Class H (Strength 8)
Number and Location: 1 Rear of Cockpit.
Cloaking Device: Class 5 - 100 power/round/use (18 SU).
Forward Disruptor Array
Type: 6 (28 SU)
Damage: 140 - 14 power
Number of Emitters: up to 3 shots per round
Auto-Phaser Interlock: Accuracy 4/5/7/10
Range: 10/30,000/100,000/300,000
Location: Forward
Firing Arc: 360 degrees forward
Firing Modes: Standard, Pulse
Forward Dorsal Disruptor Array
Type: 6 (28 SU)
Damage: 140 - 14 power
Number of Emitters: up to 3 shots per round
Auto-Phaser Interlock: Accuracy 4/5/7/10
Range: 10/30,000/100,000/300,000
Location: Dorsal
Firing Arc: 360 degrees dorsal
Firing Modes: Standard, Pulse
Aft Dorsal Disruptor Array
Type: 6 (28 SU)
Damage: 140 - 14 power
Number of Emitters: up to 3 shots per round
Auto-Phaser Interlock: Accuracy 4/5/7/10
Range: 10/30,000/100,000/300,000
Location: Aft Dorsal
Firing Arc: 360 degrees Aft Dorsal
Firing Modes: Standard, Pulse
Aft Ventral Disruptor Array
Type: 6 (28 SU)
Damage: 140 - 14 power
Number of Emitters: up to 3 shots per round
Auto-Phaser Interlock: Accuracy 4/5/7/10
Range: 10/30,000/100,000/300,000
Location: Aft Ventral
Firing Arc: 360 degrees Aft Ventral
Firing Modes: Standard, Pulse
Port 'Wing' Disruptor Array
Type: 6 (28 SU)
Damage: 140 - 14 power
Number of Emitters: up to 3 shots per round
Auto-Phaser Interlock: Accuracy 4/5/7/10
Range: 10/30,000/100,000/300,000
Location: Port Nacelle 'Wing'
Firing Arc: 360 degrees forward
Firing Modes: Standard, Pulse
Starboard 'Wing' Disruptor Array
Type: 6 (28 SU)
Damage: 140 - 14 power
Number of Emitters: up to 3 shots per round
Auto-Phaser Interlock: Accuracy 4/5/7/10
Range: 10/30,000/100,000/300,000
Location: Starboard Nacelle 'Wing'
Firing Arc: 360 degrees forward
Firing Modes: Standard, Pulse
TA/T/TS: Class Alpha - 0 power/round (6 SU)
Strength: 7
Bonus: 0
Shields (Forward, Aft, Port, Starboard) (20 SU x4)
Shield Generator: Class 2 (Protection 350) - 120 power/shield/round
Shield Grid: Type C (50% increase to 525 protection)
Subspace Field Distortion Amplifiers: Class Gamma (Threshold 150)
Recharging Systems: Class 1 (45 seconds)
Backup Shield Generators: 4 (1 per shield) (4 SU)
Auto-Destruct System (3 SU)
AUXILIARY SPACECRAFT SYSTEMS
Shuttlebays: None
Captains Yacht: No
The Theta Class is a light vessel designed in a support role for the Romulan Navy. Roughly Comparable to the Starfleet Runabout, the two designs share many similarities. However the Theta class is used as a Shuttle, long range transport and courier and as an exacutive shuttle. While its Tactical systems may be light, it serves its purpose both within the Romulan Navy and for Senatorial duties, any loss of weapons advantage is more than re-couped with the strategic use of its cloaking device.
I'd also pegged it at size 2 myself, but in designing it using the DS9 technical manual, only a single specification fell within the size 2 bracket.
So I considered this, along with the conversation on this board a while back concerning the odd 'size rules dont apply here' question, and eventually decided that the ship was larger than a rnabout and did deserve to be a size 3, although on the small end of size 3...
Good thing too, the SU's wouldn't have been enough otherwise. Sure it could have had a cloaking device, just like we saw on TV, but not enough power to run the thing...