Should I use MS or not

Before even asking this question, you should ask yourself what kind of hosting you can offer. 500 sites on a single install will slow down the hell out of everything if your host can’t keep up.

Do these clients share the themes? If not, a separate installs on separate accounts would be the best way to go since you can modify each account the way you like it. This gives the clients the freedom of doing their own modifications as well. Also if anything goes wrong, all your eggs are not in one basket so you don’t have to deal with 500 down sites at one time.

I’m assuming you have a team of 50 people working on this project otherwise it will take a a century to finish.

Ok I guess your right. I should just do separate installs. As far as hosting what to you recommend for a project of this scale? I obviously don’t want a Shared hosting account as I’ll get flagged for usage abuse very quickly with that many sites, That leaves me with 3 options Dedicated Server, VPS, or a Dynamic Cloud Server. I am really liking the idea of a dynamic cloud server, because I can increase the processor, storage and ram at any time, which makes it scalable. What do you recommend?

Minimum VPS but I would go with DS. I don’t have much experience with cloud hosting so I can’t comment on that but as far as a good host goes, I use Inmotion Hosting for all my clients and my own sites. With a volume like this, you want the best customer service you can get and Inmotion in my opinion is the best to go with. Of course you can check out the “Official affiliate hosts” listed here: https://www.ads-software.com/hosting/ as well.

Stay the hell away from GoDaddy if you value the hair on your head.

Do these clients share the themes? If not, a separate installs on separate accounts would be the best way to go since you can modify each account the way you like it.

You can still modify each theme for each client how you want with Multisite, actually. And if you use an edit CSS plugin, they can tweak the CSS locally, though not the main theme.

For example, I like to modify the login page of the WordPress to match the site. I do that by using the function.php and no plugin. This only works for one theme at a time. Many other modification to the theme individually can’t be done only for one site on a network when many other sites use the same theme.

Without knowing what you put in your functions theme, shirazdrum, I can’t speak for that, but I know you can style your login page on Multisite ??

https://wpmututorials.com/plugins/style-your-signup-page/
https://www.ads-software.com/extend/plugins/smithers-login/

(there’s no real diff between a function.php tweak and a plugin, when you get down to it)

well this is an example for my own site at https://dreamdare.org/wp-admin

<?php
function change_login_css() {
  echo '<style type="text/css">
    h1 a {
      background-image: url('.get_template_directory_uri().'/images/login-logo.png) !important;
	  height: 142px !important;
    }
	.login #login a {
      color: #CCC !important;
    }
    .login #login a:hover, .login #login a:focus {
      color: #FFA500 !important;
    }
    #loginform label {
      color: #CCC!important;
    }
    #loginform input:focus {
      border: 1px solid #FFA500!important;
    }
	body.login {
	background: url('.get_template_directory_uri().'/images/darkhive-bg.png) repeat;
	}

	.login h1 a {
	padding-bottom: 55px;
	}

	#login {
	padding: 84px 0 0;
	}

	.login form {
	background:#1A1A1A;
	border: 1px solid #333!important;
	-moz-box-shadow: none!important;
	-webkit-box-shadow: none!important;
	box-shadow: none!important;
	}

	.login #nav, .login #backtoblog {
	text-shadow: none!important;
	}
  </style>';
}

add_action('login_head','change_login_css');

function change_login_url() {
  echo home_url();
}
add_filter('login_headerurl','change_login_url');

function change_login_title() {
  echo get_option('blogname');
}
add_filter('login_headertitle','change_login_title');
?>

the reason I said that is that I like to make themes as light as possible. I don’t like function heavy themes, arsenal of plugins and user interfaces for adding header images, or modifying simple things.

I like to hard-code everything inside my themes so they are unique and not usable for other sites right out of the box, yet they perform as fast and efficient as I like them to be.

shirazdrum – You’re definitely one end of the use-case spectrum ?? You’re not doing anything wrong, but your way is not the only way, and it’s best to offer up the multiple paths to possible happiness ??