Often key changes are made and announced, but a stats page maintainer might miss this, or his remailer isn't automatically updating with new keys and purging old keys. With new remailers coming on line all the time and others departing the network after only a brief appearance, it can be very difficult to maintain an accurate list of exactly which remailers are really online. Also, when a remailer joins or leaves the network, the uptime and latency stats for that remailer will not respond instantaneously. Stats are an analysis of data taken over several days and presented as a moving average. Some stats pages are in question 5.3.
Different clients read different stats.
There isn't a really big difference between them. Version 2 is somewhat more detailed and uses different symbols than Version 1 to represent the measurements of Latency, History and Uptime. You may also download TXT versions of each. Most users need only consider which stats version their client will read. Here is a summary of the recommended version.