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Do you have any step-by-step instruction how I can reliably reproduce the issue?

I only had problems myself when I added new snippets to TextExpander which were then not immediately recognized in Textastic.
It seems to work now.

Sent from my iPad :)
There is a list of shortcuts supported by iOS in the manual: http://www.textasticapp.com/manual/lessons/Which_keyboard_shortcuts_can_I_use_with_an_external_hardware_keyboard.html

This includes Copy, Paste, Home and End shortcuts.

Note: Unfortunately, these shortcuts are entirely provided by the iOS operating system and there's no way for third party developers to extend them with custom shortcuts.

I've sent a bug report regarding the forum on iPad to the UserEcho guys. It used to work on iPad but it looks like they changed something recently that broke it.
For me it works on the iPad. What didn't work for you?
I didn't have this problem with my own folders that have spaces in them. Which server software are you running? Do you just have to go into a folder to make it crash or do you have to download or upload files?
Texastic (or actually libcurl) keeps the connection alive for reuse for the next operation. This is done because authentication takes quite long and reusing connections speeds up everything dramatically. Actually, the file should be closed by the server after an upload is complete even when the connection is still alive.

Which server software/ssh server are you using? Maybe I can reproduce the issue and find a workaround.
Here is the full version (512x512). I can assure you that it was a lot of work - I've seen the amount of layers in the Photoshop file :)

Actually, the icon was created by the guys from Softfacade (http://softfacade.com/) who are well-known as one of the best icon designers in the world...