Knowing what some of my small business clients are like, getting the annual accounts out of them for submission on time can be a stretch. Reporting more often is there going to be an "interesting" experience all round.
For those businesses registered for VAT the new regime will probably be no big deal. Quarterly reporting is required. For other businesses I reserve judgement.
This assumes Britain actually leaves the Single Market. We must wait and see. The situation is so muddled and fluid politically anything can still happen - and probably will.