The target audience has nothing to do with the engine as well as the type of game.
More important are talented people in your team - but not only graphics guys. It is very important to have at least two people in a team which have excellent knowledge of the engine you are using to really have a motor in your development. Imagine a programmer who drives the project and then he leaves or he is ill or whatever. So you have everytime a fallback person. You should also consider if you build a local team together in one office or if you are spreaded and you really announce hardworking weekends (from 8 AM to 3 AM) one or two times a month to compensate crunchtimes or if you take the risk to rely on a spreaded team. It is also a cost factor. Even if you have theoretically 100k euros... you have to pay software licenses (A6 team edition, Maya/Photoshop.. etc. licenses if you employees dont own them already legally), website hostage, office costs, charge for gasolina if your members come to you or so, hardware (you cannot work with a member who has a crappy PC from 1995 ^^), of course the money to pay your teammates, etc.pp.
It is also a difference which type of technology you choose. Let us say you want to develop your game with an open source engine like Ogre or Irrlicht just to name two major brands in the OS scene: you can enhance it if you have the skilled persons and behind them there is a very vivid community which pushes those engines forward. The risk of them is which leads us toward commercial engines. The are relyable.
Actually, gamestudio is one of the most used and developer friendliest engines on the planet. Ok, most people will come now and blame it, but we know the pros and cons and we debated long enough about it. So, if GS fulfills your needs, use it. When you started your project with it, finish it. It would be a horrible case when you switch the engine. YOu dont just have to port it, but you have to learn it. Learning curves and so on. If you have skilled people again in your team which know the other tehcnology - good. But also suboptimal.
I see no reasons why gamestudio isnt good enough to be used in a professional product. There are hundredthouasands of sold copies of games which are developed with 3D Gamestudio. So I think its reasonable - I say that also because I'm involved in such a project so my arguing is purposed by that fact. Nevertheless - it doesnt count for your (theoretically
) decision.
serious greetings
Christian