The incremental search as implemented for single file is indeed very nice, but in case of multiple files I believe more useful would be just list of files, where searched string was found (including figure indicating number of occurances for each file). The search within individual files will come into play after user clicks one of the files in the result list. User should be able to go through all the occurances of searched string easily.
This is all the requiments I have.

This is indeed the most needed function for anyone working on a set of documents.
I'm a developer and I'd really love to have the whole API of a large commercial application for reference when on the go.
I have my iPad always with me and Textastic is perfect for me. The only missing and very important feature is ability to search within multiple documents in multiple (sub)directories. Support for regular expressions is welcomed, but even simplified versions of regexp wiould be enough for the beginning.
Thank you for your work!
Jan