With the no-purge method, at what rate would you recommend collecting the samples if there is plenty of volume in the well?

The sampling rate should be the purging rate for larger bottles provided it’s not excessive. For example, if you purge a well at 500, 600, or 700 mL per minute, use a 500 mL per minute rate for larger sample bottles and reduce the rate to 150-200 mL per minute to take any other samples. But, your sampling rate generally is going to be at or below the purging rate of the well. You can’t increase it because, of course, this means you would be increasing drawdown in the well and then you can lose your stabilized conditions.