Try to keep products to 500 or less if you have variation heavy products and you shouldn't have problems. But your hosting is another factor as well.
I have 8 stores with approx 300 products each..maybe half of them with a few variations. I have had no problems so far...but my sites are slowly growing with more products so I anticipate problems in the future.
That's why I am biting the bullet and going back to the Original plugin.
Thank you
"WELL KNOWN ACTIVE MEMBER"
I was worried about adding products with 8-10 variations. Almost 25% of my products are with 8-10 variations and rest of them are below that. My hosting is with Siteground and till now my CPU usage stays under control until I use manual update. As you are running 8 stores, I am very sure that these variations are not going to hurt before 500 products.
I wish I could use original plugin, but the themes are not suitable for my store and I am not good in coding at all. Nor I have a budget to hire a freelancer. So, I have to start with woocommerce only. I am hoping for the best and I will also shift once I start getting enough sales.
Thanks once again