Scoundrel

I may get flamed for this, but since DPS Scoundrels are equivalent of WoW Rogues, it may help to understand the TOR counterparts of Rogue abilities.

Shoot First = Ambush

Back Blast = Backstab

Upper Hand = Combo points

Blaster Whip = Sinister Strike - upper hand builder.

Sucker Punch = Eviscerate - Not exactly same, but a upper hand consumer.

Tranquilizer = Sap

Disappearing Act = Vanish

Hemorrhaging Blast = Hemorrhage

@Shubawks - Yes, all healers can be effective main healers. Scoundrels are the HoT (Heal over time) based healers and as per recent theorycrafting, they are the most resource efficient healers on the Republic side.

Here's some beginning math on healing with a Scoundrel. My disclaimer is that I am currently level 37, and am wearing quest/commendation badge armor, and I don't know how the math scales as you level. Also, there are other game mechanics that I don't fully understand. For instance, I have a 50% base crit multiplier that I have no idea from where that comes.

On the character sheet, it seems that there are 4 relevant sections of the Tech aspect of the Scoundrel. The Ranged and Defense aspects do not affect healing, and I'm ignoring the PVP section for this comment, so I'm only focusing on the Tech portion of the character sheet. However, if you are a PVP player, you will want to also look at this aspect as it does have an impact on healing in the PVP setting. The relevant sections for my comment are: Bonus Healing, Critical Chance, Critical Multiplier, and Activation Speed.
Bonus Healing:
1 point in Cunning (primary stat) adds 0.14 bonus heal (7.14 points = 1 bonus heal)
1 point in Power adds 0.17 bonus heal (5.88 points = 1 bonus heal)
1 point in Tech Power adds 0.17 bonus heal (5.88 points = 1 bonus heal)
This means that Power and Tech Power are equal in terms of impact on bonus healing.

Critical Chance: This is the increased chance that your heal will be a critical hit.
1 point in Cunning adds .0098% (102 points = 1% increase)
1 point in Crit Raiting = .055% (18.18 points = 1% increase)
The Scoundrel "Lucky Shots" buff adds 5% crit chance increase

Critical Multiplier: This is the percentage that a critical hit increases healing amount.
1 point in Surge Rating = .267% (3.74 points = 1% increase)

Activation Speed: This is how quickly you execute skills or how long it takes to channel an ability
1 point in Alacrity Rating = .05% (20 points = 1% Alacrity increase)
Black Market Mods gives a 4% increase in Alacrity

From this, the secondary stats a Sawbones should look for are Power, Tech Power, Crit Rating, Surge Rating, and Alacrity Rating.

From what I've seen from Beta Testers thus far, presence is primarily related to Companion interactions. You'll want to increase this for much of the solo-questing in the game I would think. However, it seems that each class has a single primary stat that will enhance the capacity and abilities of said class. In this case, it would be Cunning. Alacrity is how fast you do things (think haste from WoW) and I think would be relegated to more a secondary stat. However, I'll include more accurate information after I can get my hands on the class during the Stress Test beta weekend this weekend.

Update 11-28-2011: Cunning is the primary stat of a Smuggler, regardless of the advanced class you choose. The only consideration I would include is that Aim (Trooper/BH primary stat) also affects Smuggler DPS. While it doesn't provide as much of a benefit as cunning, it could potentially have uses. However, Alacrity, Surge, Crit, and Hit should be considered secondary stats. It appears that a Sawbones Scoundrel is unlikely to stack much Hit; however, given the interplay with Upper Hand and healing, we may find healers trying to achieve a certain hit breakpoint.

Aside: It seems like the "Reply" function isn't working properly as this comment was supposed to be a response to kilzaar's question, but instead posted a new comment instead of chaining to the comment to which I was replying.

Looking at the trees it seems to resemble the trooper/hunter set up were tactics is close in melee spec and assault specialist is more mid range.

Does same hold true here? Scrapper is melee and positional depentant were dirty fighting gives more mid range damage?

tl:dnr who much do i use back blast if i spec dirty fighting?

^ DubbaCV - I've also noticed that.

As for the actual Scoundrel class, does anyone know what kind of limitation they have on healing? If I had a group doing some sort of instance, would it be possible to have a Scoundrel as a main healer role in the group?

From my limited play time in the beta, Scoundrels can make excellent main healers and are most comparable to the Resto Druid in WoW. The energy mechanic is a little strange to get used to but consistent use of Upper Hand and Pugnacity makes the healing mechanic very satisfying.

DPS wise these guys play very much like a Rogue (as detailed above). I wish Scatterguns were visible at all times though.

Also to the above posters, the Sage is by far the better healer. They have stronger heals, damage shield and much much better regen with a bigger "power" pool.....In fact the only thing that scoundrel can do better is spam emergency medpack when they are under 30 percent. They do wear medium armor and they have stealth which I guess makes up for the difference in healing ability. But imo these are mainly pvp abilities and not related to actual healing at all.

None of this means the Scoundrel can not main heal. They are just inferior in most respects to the Sage in straight healing.