Obviously there are many variables.. just wondering if there are any blog posts out there or if anyone would be willing to share their numbers? Is 10% a reasonable expectation? This is assuming a monthly subscription model with no free plan.
Conversion is primarily based on value of the product to the user and the price. If its valuable and free, you can expect maximum conversion. If it is arguably valuable and not free, the conversion rates will generally go down as the price goes up.
Suggesting there is any reasonable expectation in general is really not at all possible. Find comps for products that are the same or similar, check out their prices and find out their conversion rates. Only then can you start to formulate a reasonable expectation for your specific product.
The main variables are the length of the beta testing and the involment of the beta testers community.
If you provide good support and listen to their needs, 10% is not unreasonnable but giving good support can be very hard, depending on the size of the community.
I would use 1% as a basis -assuming the service really serves a need- and go up from that, depending on the available resources for support.
In that case why don't you pre-qualify all of your beta testers as customers?
10% would be on the low side if you've got people actively using your product to improve their business. You can easily hit 100% adoption by droppping the price for active users lower and lower till they all adopt.
Suggesting there is any reasonable expectation in general is really not at all possible. Find comps for products that are the same or similar, check out their prices and find out their conversion rates. Only then can you start to formulate a reasonable expectation for your specific product.