Entering US with ESTA only, when B1/B2 visa would be required

Obligatory correction - ESTA is just permission to get on a plane. It is the Visa Waiver Program (VWP) that allows you to enter the US without a visa. People often say they are "going to the US on an ESTA" but technically they are entering under the VWP, for which having an ESTA is usually necessary. If you are researching the conditions of your entry look for the Visa Waiver Program, not ESTA.

All activities that are permitted on a B1/B2 visa are permitted under the Visa Waiver program. So if a B1/B2 was sufficient for your travel then the VWP will be sufficient also, with the following conditions:

• You must be a citizen of a country that is eligible for the VWP.
• Your visit must be less than 90 days
• You must not be excluded from the VWP for any other reason. This includes previous denials of US visas, or connections with or visits to excluded countries.

For more details start at this page.

The activities allowed under the Visa Waiver Program (the program that you enter the US with when using an 'ESTA') are exactly the same as those allowed when entering under a B1/B2 visa.

The only situations where a B1/B2 visa would be required for someone that is eligible to enter under the Visa Waiver Program would be if you were wanting to stay for more than 90 days, or if your ESTA application was denied. (There are also a few other corner cases around change-of-status once you're in the US, but these are generally not relevant).

Thus presuming you are not planning on staying more than 90 days, there is zero additional risk for you entering the US using an ESTA than using a B1/B2 visa.