Superrack is an excellent way to access Waves high quality plugins without the higher budget hardware. For people on a budget, Superrack offers all the functionality you need to pair with a digital mixer to get some excellent outboard processing. I've been using this now for 6 months in combination with the Waves Ultimate subscription - and I am very pleased with the stability and latency. The only limiting factor is that for very large shows that use a LOT of plugins, you do need a pretty powerful PC. If you have a MacBook Pro with 'M' series processor - you will find this works extremely well, and even with low latency quite a number of plugins can be used before processor loads become an issue.
In summary - for mid-sized live or studio use, Superrack is an excellent proposition. The software is very intuitive, and combined with a subscription, this becomes a very affordable and unbeatable solution.