Hi Dominik:
I may totally understood your situation right now because I was using QTP for a long time and now I'm using TC to test Delphi application that recompiled by Delphi XE.
QTP and TC are different from object hierarchy perspective.
1. QTP wrapped all objects start from application level such as Window(IdenAttr).Button(IdenAttr1) or Browser(IdenAttr).Page(IdenAttr1).WebEdit(IdenAttr2) things like this, but TC gives you all objects start from system level such as Sys.Process(YourApp).Window(IdenAttr).
2. QTP and TC are using separately internal functions or objects to support itself automated script.
3. TC does not support Descriptive programming.
4. TC support Delphi application testing better than QTP based on what I'm understanding right now.
5. QTP product maturity level higher than TC
6. You may create user defined objects in your framework(little bit hard then you think) and implement them in TC or rewrite your framework(I'm doing redesign now).
7. QTP and TC both are using VBScript engine, so they are identical from VBScript perspective and totally different from implementation perspective.
Good luck,
Allan