I've had good luck using Visual Basic 6 (COM-based, 1999) as an alternative to ExtendScript or VBScript for scripting Indsign CS4.
I've been experimenting with the new dynamic type in C# 4.0 and have had some success in scripting Insign CS4.
It's far from ideal - no intellisense or enumerated constants. Have things improved with CS5?
Has anyone else tried using .net to develop scripting apps?
The old VB6 IDE provides great intellisense from the indesign typelibs.
Allows for exploratory programming without have to browse endless reams of api documentation.
Sure wish the ExtendScript IDE provided intellisense.
You can try the CS SDK in Flash Builder if you are looking for code completion...
Some folks in our team use JetBrain's IntelliJ or its smaller sister WebStorm, others even NetBeans.
For code completion you'd need to convert the omv.xml. I do not like/use code completion because I hate it if I type a key and the editor pops up windows and inserts something completely different. Therefor I do not know about any details of the mentioned conversion process.