You will need to be clear when you go for groups. In beta, players asked for heals instead of a sorc. Sorc is not the only healing class, and it does cover ranged "magic", so for those who are from WoW, you might think Mage. Every group needs the fundamental roles of tank, dps, cc and healer. I've been in groups where we used Khem Val as the tank and things worked (it was challenging, but we pulled it off). The great thing about SW:TOR is that there are several classes who can heal, and several who can tank, or dps. I would imagine that when lfg, you will hear players asking for role fillers instead of specific classes. The exception is that for tough Heroics, you will need a specced healer because a hybrid won't be able to keep the tank healed. I have several years of healing and tanking experience, and was in beta for a year. (Just saying I am decent at playing a healer.) And there were some Heroics where even with a spec'd and geared tank, keeping him up was challenging. Early on, a few were simply brutal. I think they have things tuned pretty well by now. Past L20, you will want to have specced roles for the most part. Hybrids will have challenges unless they are really good. The coolest groups I was in had SI's for all 4 spots with an Assassin tank, Assassin and Sorcerer dps, and a Sorcerer healer. Those were amazing!!!

Presence was the healing stat early in beta, they changed to the main stat for the class to cover both healing and damage, and for SI's, that is Willpower. A Corruption Healer can do decent dps with Khem Val as companion. Use Khem to grab and hold agro, then dps while he tanks, and be sure to heal when he gets to a certain level. You essentially have your own mini-group. Be sure to keep him geared, and the best way is to grab the Khem Val specific drops from quests. Most of the time, they are good upgrades. Check every time though because sometimes those will be a minor upgrade and you might want to take an item for yourself. I did notice in the last build that droid gear was rewarded in several quests, and some people did try using the ship droid as a healer. It was late in beta though, so that may be a good option if you want to dps or tank as an SI (tanking requires Assassin though). Some of the heals appear crapptastic to start, but they scale well with level. The heals work together well. For a tougher mob, I would shield and toss a regen on (sorry, I don't remember the spell names), and then dps and watch, when Khem's health dropped slowly below 50% or if it started dropping fast when the shield fell, I would start the big heals. It's very similar to healing with a priest in WoW. Oh, and for big groups of mobs, you may need to cc as well. The Sorc has good cc ability on top of everything else. If you understand the fundamentals of group play (I know a lot new to MMORPG's won't, and don't worry, it comes with practice) and agro management, leveling a full healer SI with a geared Khem Val is very efficient and a lot of fun!!!! I won't drop a spoiler, but I will say that it was late in leveling before I changed my main companion. Khem is a pain in that he hovers and stays close, and you always seem to be mis-clicking on him.. moreso than any other companion; but once you get used to him, he is one of the best solo'ing companions in the game, in my opinion.