InfoPath Dev

What is the reason that enterprise (paid) feature Web Browser Enabled forms in Infopath lack Master/Detail control containers present in free Infopath Filler (client) forms?

Is it some conceptual impossibility and I should choose client (browser-disabled) forms if I have requirements for compound Parent/Child views designed in Infopath?

What are the factors for chhosing Infopath Filler 2010 created (client) forms over Browser-enabled Infopath Designer 2010 forms or vice versa? 

I am confused by the fact that the free Infopath Filler 2010 created (client) forms have access to richer pool of functionalities than (paid or available as part of enterprise Microsoft Sharepoint 2010 Server) Web Browser-enabled Infopath Designer 2010 forms. For example, Master/Detail control container is available for client forms but not for Infopath Designer 2010 forms.  And I do not grasp why and what are implication on deciding which of them use. 

All my clients have Infopath installed locally and my company has enterprise Sharepint Server 2010 (with access to"Sharepoint Infopath Services" running)

In InfoPath (client), all controls can be supported and displayed properly. In the browser some controls cannot be rendered, some functionality is not available, because the form needs to be rendered into html.

Here is a compat matrix from Microsoft:

http://office.microsoft.com/en-us/infopath-help/infopath-2010-features-unavailable-in-web-browser-forms-HA101732796.aspx

So if you absolutely need functionality that is only available in the client, then choose the client. :)

I couldn't say specifically why Master-Detail isn't supported in the browser, though it is comparatively complex functionality.

It is possible to produce browser-compatible master-detail-like functionality with a little bit of extra work.  It would go like this:

1. Design your repeating group so that it has a field that's unique in each row (such as an incrementing row counter)
2. Create a field outside the repeating group (preferably in a secondary data source if you know how to do that) with a name like SelectedRow
3. Add a button to the rows of your Master table that says something like Show, and whose action is to set the SelectedRow field to the value of the unique field in the repeating group
4. Add conditional formatting to the Detail table (section) like this:
     Condition: UniqueField is not equal to SelectedRow
     Formatting: Hide this section

My Self The Enemy:

I am confused by the fact that free Infopath Filler 2010 created (client) forms have access to richer pool of functionalities than enterprise (paid) Web Browser-enabled Infopath Designer 2010 forms. For example, Master/Detail control container is available for client forms but not for Infopath Designer 2010 forms.  And I do not grasp why and what are implication on deciding which of them use. 

 To respond to your confusion, the fact of the matter is that there are some features that are harder (or impossible) to implement in a client-server web application vis á vis a freestanding rich client.  That's why the client version has all the features the browser version does.

Many people like the ability to fill out forms in the browser without having InfoPath installed or having Office Premium licenses, but if everyone at your organization already has InfoPath, then client forms may be the way to go.

Jimmy:

 To respond to your confusion, the fact of the matter is that there are some features that are harder (or impossible) to implement in a client-server web application vis á vis a freestanding rich client.  That's why the client version has all the features the browser version does

Can I ask to specifically mention the features of client (Infopath Filler 2010) forms that are impossible to reproduce in (Infopath Designer 2010) browser-based forms in context of their use with (enterprise) Sharepoint Server 2010? 
or will cause problems during their deployment into production?

I guess that browser-based forms should have issues with performance and double hop (authentication) problem.
The former (browser-enabled form) communicates with server via stateless XMLHTTP protocol in contrast to client forms communicating via NT LAN Manager NTLM .

AFAIU, browser forms do not have abilities to pass user credentials to a remote server. 
"Infopath Form Services" (IPFS) of Sharepoint Server 2010 has web proxy service for IPFS for this but I do not quite grasp how Sharepoint Server 2010 in this case might treat concurrency, i.e. simultanious filling of the same form by multiple users.    

It is better to be specifically forewarNed especially for developers like me having all servers and clients in the same machine