[sorry] potentially REALLY dumb question - re: wordpress...

If memory serves me, I sure you can transfer the information from one site to the other using FTP.
You can check this article and see if it helps
Copy Your Web Site Using FTP

Moving a WordPress blog is more than just copying files over with FTP. There is the database to handle as well, which is where your contents are kept. You should follow the instructions here on how to do so, it's step-by-step easy to follow:

Moving WordPress « WordPress Codex

Based on experience, you might run into some theme problems if you're using a heavily modified theme, but those are usually easily avoidable/fixed by making sure your installations and plugins are up to date on both sides

First, the only dumb question is that not asked so don't sweat it.

I've used the process above and while it works - HUGE PITA

I just use "WP TWIN. Takes all of a few minutes.

I know you mentioned you're looking for ways "other than cloning scripts..."

But why?

It's easier and being easier = time saved and time saved is money earned.

Well, to start you should be able to wrap the template you are developing on zip file.
Then simply install a freesh wordpress on your clients domain, and install your template to the main site, at least is what I do.

Unless you have tons of data on the demos site that are souposed to go live, the moving site is an option, yet there are plenty of plugins to move contet only.

But essentially if you don't want o work twice, you will use dummy data in the demo site and create the "official" dataset in the live site. So focus on creating a featured template, neve create files outside your /wp-content/themes/yourTemplate directory, and when you are done, you should be able to easily zip and upload your theme to the new site

Yep, very much doable, I've done this a lot many times (before I ran into WPTwin of course).

Wordpress has two parts - files, database.

Files - everything under "MyDomianName.com/client-name"
Database - the database mentioned in your wp-config.php file

The dirty way -

1) Copy your files to ClientDomainName.com
2) Export your wordpress database (include every table and data in it) as an SQL (.sql) file. You can do this using PHPMyAdmin if you have it (or practically any database tool which can connect to your database)
3) Change any reference of "MyDomianName.com/client-name" in your database to "ClientDomainName.com" (You can do a search and replace by opening the .sql file in notepad).
4) Import the database on to your client's database server (You would usually have PHPMyAdmin on your client's end to do the import).
5) Point ClientDomainName.com/wp-config.php to the new database, userid and password.

It should now start running. I call it "the dirty way" because you might run into some minor hiccups and takes time to do .

Hope this helps.

A quick search on Google reveals a number of free cloning plugins.

https://www.google.com/search?q=word...cloning+plugin

So you just want to do Theme design change.

In that case database won't be a prob much.

Install the theme on sub-domain, do the CSS or some PHP changes, save it and then from Cpanel/FTP compress the WP files in the sub-domain by going to wp-content/themes.

Then download that compressed zip file to your hard-disk and then upload to your main domain.

I would suggest you to develop site offline, locally and then upload it online. Once you upload it just replace localdomain with realdomain in DB and you're good to go.

WP Clone works well and is free - the only thing it didn't copy on one of (far too many) sites I copied recently was an extra page that I'd added the theme & that was a simple extra FTP transfer.

Install it on the working copy and do a backup.

Install it on a fresh copy of WordPress on your new host and do a restore, ticking the boxes with the dire warnings about backing stuff up etc.

If necessary, change the domain name settings by going directly into PHPMyAdmin (they're in two places but are quite obvious)