Thanks for considering AcuRite, we are finding more and more people trying out our products as replacements for higher-cost units, we have received allot of positive feedback.
The 01010 display console does have daily and all-time highs/lows. The daily highs/lows DO clear out at midnight. Push the "records" button once though and you can see all-time highs/lows with a time/date stamp. These records are kept until they are either manually cleared or they are broken by a new record. I also recommend adding our web-bridge when it becomes available, it will give you options like charting and publishing to weather underground. Should be available sometime in september as an add on to most of our weather systems, and it will give you access to complete records and history from your PC and/or smartphone. I am finding I am using my iPhone more and more to look at my weather and data with my early alpha test web-bridge. I can see a quick view of the last 12 hours, last 12 days, 24 hour average, 24 hour change (-/+)- and tap once and see weekly, monthly and yearly records, as well as set email and text message alarms. And if I want to see even more detail, I can go to the webpage version and I can chart with comparison options very easily- all on a nice bright interface- for free (web bridge will be around $60.00 and connect your wireless sensor directly to your router, or use USB version to connect to your PC)
Our 01500 and 01015 products have a more highly-featured display than the 01010, with a "weather-ticker" display that gives you more detailed history records. These are larger display consoles with backlights and AC power & battery options, but they are higher price (~$130.00)
There is a calibration option for temperature and humidity (indoor and outdoor) on the display console, and mechanical rain gauge calibration integrated into the Vn1 wireless sensor, although we have found both to be really accurate out of the box most of the time.
Also note that the sensor is internally fan-aspirated (runs off of a solar cell), although a roof top mount will likely heat it up a bit. Mount the Vn1 unit up high and on a sturdy pole/mounting location. I have mine mounted in an open location, about 14 feet up on a collapsable flag pole with a reducer. Temperature will not vary too much at that height, but it makes a big difference for the wind measurements. If it is not on a sturdy mount, the rain gauge will probably register higher due to wind/movement.
Let me know if I can answer any other questions, I hope you find our weather station to meet your needs!