The only time using the EIN may prove to be an issue is if you become subject to backup withholding by the payer, they would submit that withholding under the EIN, but since you're an SMLLC you'll be filing a tax return under your SSN.
IRS computers may not be able to automatically cross reference payments submitted under an EIN with the SSN used on a 1040 and send a letter out prior to releasing any refund for that backup withholding.
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