NetAccess is useful when you have something which is difficult or impossible to program in APL+Win but is easy to perform in C# with Microsoft .Net.
There are many things which fall in this category and most of them are related to using new technologies which APL+Win is not adapted to deal with.
I am not saying that all of the above is impossible to do in APL+Win (Davin Church has written workspaces to solve some of these problems and I did too with my objects) but when it is possible, it requires considerable efforts Doing the same in C# most often requires only a few lines of easy coding, just because there are classes in the .Net Framework that have been built by Microsoft to do the job.
For example, Regular Expressions are an extremely powerful feature which can help do a LOT of things in an application and it is totally absent from APL+Win. Writing a C# DLL which allows to use Regular Expressions in APL+Win is a simple task.
Another example: my TEmail5 object was able to send Emails and even to do E-mailings, however it would take about an hour to do an E-mailing to 1000 recipients with TEmail5 and the TEmail5 code is long and complex.
I wrote TEmail C# and its only a few lines of code and it can do an E-mailing to 1000 person in about 1 minute! The reason is that, not only C# can use .Net Framework classes which have built-in methods and properties to do the job, but also it can do it asynchronously (which APL+Win cant).
C# does not replace APL+Win though and as a matter of fact C# is less efficient than APL+Win for a number of tasks, notably array calculations and handling and file usage (colossal files are so powerful).
So, NetAccess is more of a tool that I would use only when it is easier to do something in C# than in APL or when the program performance would be much better in C# than in APL (as is the case for TEmail for example).
To let you better understand: if I have to write a complete application now, I would probably select APL+Win as my development system, would write maybe 80% of the application in APL+Win and would probably identify a number of places in the application where it would make a lot of sense to write things in C# rather than in APL. For those tasks, I would use NetAccess to create C# DLLs which I would then call from APL+Win.
I am saying all that, in order for you to see by yourself, where NetAccess could be used in the scheme described by your ../cloud/netaccess.htm page.
The problem is that there are thousands and thousands of classes in C# and we even ignore a lot of all what we could do with all these objects.
It is probable that using some of them would simplify and speed up a good number of places in an APL+Win application. NetAccess can be used to write all these C# DLLs which would simplify and speed up writing a new APL+Win application or improve an existing APL+Win application.