On-the-spot, light-touch inspections will ease the burden on teachers and are overwhelmingly supported by schools that have experienced them, a TES survey reveals.
But the experience of more than 50 schools shows that heads face a heavier workload as a result of the new framework, which places greater emphasis on school self-evaluation.
There are also concerns that the new inspections do not allow inspectors enough time to form an accurate picture of schools.
Under the new framework, which will be introduced in September, schools will typically be given only two days' notice of inspectors' arrival, compared with six to 10 weeks at present.
Inspectors will spend less time in school, and will undertake fewer lesson observations. Their role will be to check the accuracy of schools'
The TES surveyed 104 nursery, primary and secondary schools that have piloted the new arrangements since summer term 2004. Just under half of schools responded.
Nine in 10 rated their experience under the new framework as better than previous inspections, and just two schools said it was worse. Schools said the new inspections were "done with us, not to us" and praised the quality of Her Majesty's Inspectors, which led the pilot inspections.
Eight out of 10 said the new arrangements made inspections easier on teachers. Three-quarters said they put more pressure on senior management.
Steve Welton, head of Birkett House special school in Wigston, Leicestershire, said: "It was more an inspection of management and the function of management as the nervous system of the school."
The shorter notice was welcomed by 90 per cent of schools, although some admitted that because they were taking part in the pilot they had a good idea when inspectors were likely to arrive.
Heads said it provided inspectors with a "warts and all" view of schools and reduced paperwork.
Peter Kubicki, head of Cordeaux school in Louth, Lincolnshire, said: "It avoids the paralysis of weeks of Ofsted preparation across the staff.
Nevertheless, for the pilot there was an air of unreality as we knew roughly when it would be without a great deal of guesswork."
Most schools (86 per cent) believed inspectors gained an accurate picture of their performance. But one in nine disagreed, saying that inspectors spent too little time in the school to make an accurate judgement. Four of these six schools were graded no better than adequate.
George Potrykjus-Lupton, head of Roland Openshaw nursery in Newham, east London, said teachers had complained that they were not seen by inspectors.
He added: "Because of the time constraint of a one-day inspection, staff and inspectors were unable to initiate dialogue, which disabled our ability to give evidence which disagreed with their judgement."
The school was graded as good by inspectors.
From September, schools will be judged on a four-point scale: 1 outstanding, 2 good, 3 adequate, and 4 inadequate.
David Bell, chief inspector, has warned that schools currently judged to be good may only be marked as adequate under the new framework. Of the schools surveyed, 15 were judged to be outstanding, 26 were good, nine adequate and one inadequate.
An Ofsted spokesman said: "Introducing more sharply focused inspections, which place a greater emphasis on a school's own self-evaluation, will enable inspectors to concentrate inspection effort where it matters most to bring about improvements.
"Shorter inspections will reduce the demands of inspection for teachers, and the much shorter notice of inspection will reduce the preparation which was sometimes a source of pressure under the previous arrangements.
"Increasing the frequency of inspection to every three years means that parents will benefit from more up-to-date information about the quality of education received by their child."
* 6-10 weeks' notice before an inspection
* Large Ofsted teams visit schools for about a week
* Inspections at least every six years
* Extensive use of lesson observation and some use of self-evaluation
* Reports within 40 days of inspection and up to 50 pages long
* Schools have to write a post-inspection action plan
* Schools graded on a seven-point scale New system
* 0-5 days' notice
* Small teams visit for no more than two days
* Inspections at least every three years
* Self-evaluation at centre of inspection; some lesson observation
* Draft reports seen by school within a few days. Reports about 6 pages
* Schools required to amend current development plan to take account of inspection
* Schools graded on a four-point scale from outstanding to inadequate