I am working on a .Net website which is going to have 1000s of concurrent users.
I am thinking of keeping the business components on the app server and UI components on
You can check here a performance comparison between WCF and other communication technologies (including .Net remoting). The conclusion is : WCF is faster.
We use net.tcp bindings with hardware load balancing on our high traffic sites. It seems to work great and we haven't had any problems with it.
I've a project using 2 application servers and 2 front-end servers plus load balance: No problem at all. Runs fast like a thought.
The other team on my company is working in the same infrastructure. They have lots of problems... specially security ones!
.NET remoting is more or less 'deprecated', it has been dissolved into WCF. So it's not an either/or question. I suppose you should ask: what kind of WCF (binding) or whether there are other alternatives.