90% taken for one, the Shadow should only take 30% though. There's a way to control their movements, they should have their own "action tab" that you can access, so you can drag servitor actions to your quick bar.
They also have a 6 hour cooldown, at least unless they changed it in a recent chronicle (I'm still working my Dark Wizzie up too,) and only last 20 minutes of combat (80 not in combat, or something like that.) The cooldown disappears if you go full summoner at 40.
Downtime gets better at 25. Body to Mind turns your HPs into MPs. Same level you get Shadow Spark, which gives you a nice overhit spell. For this reason, getting to 25 is harder than leveling after, heh.
Preety sure i remember a 6 hour cool down before being able to re-summon pre-40. The thing i DO remember is the cool down DOES NOT end automactically at 40. You have to learn/place skill points in the respective summon to end the cool down once you reach 40. Was a nasty surprise for me, :) so if your going summoner, save the SP to do this, or be prepared to continue without a while longer.
Is it worth it to summon pre-40? My answer is depends on you. Me,,,I did just to learn how to control movement and see what it could do, so for me yes..{plus its just so dang cool} and I working with my wifes scavy, almost seems like having two pets to care and tend :)
I use the Silouette, for farming cash or manoring. {Cheaper cost 1 Dcryl to summon}
I haven't used the Souless yet, takes C-cryls now, and is an AOE summon, and I placed SP into summon buffs & heals before gaining this summon. I have it now,,but looks like almost a special party animal {AOE} to me.
I use the Shadow to level. The drain sux, but hey I play a dwarf WS too so im used to the abuse.
Similar to others most likely i have diffrent hot bar set ups, a solo, a duo, a party bar. All which are able to have the summon controls placed as hot buttons.
I also just drag the summon control box near the hot bar and leave the tab open. All the controls are there, so i don't need to place them in the hot bar.
I am by no strech of the imagination an expert summoner. My summoner hasn't got much love from me lately as the WS has taken a lot of my leveling time. :p That said, I just still love it when i get the time, but that is me.
There are many others in these boards, much more qualified to give advise. What i can tell from my experiance is a summoner { any of the classes} is VERY diverse. That being said, it takes as much patience leveling one as it does a dwarf IMO. :)