Firstly you do not need to remove wp-cache. All you need to do is exclude the forum from using it. This can easily be done on the wp-cache admin options where it allows for exclusions. This will then work just fine. just put the forum page slug in there.

If you have removed it however, then SP will operate as normal. If you are still seeing cached pages then you have not removed wp-cache completely. Just removing the plugin files does not remove the old cached pages (I believe) and, if I recall correctly, it leaves an entry in your wp-config.php file and possibly the .htaccess file as well. You will need to follow the instructions from the plugin to remove all traces. But – as I said above – there is no reason not to use it.