Mike,
Here is a spanner in the works. I actually tried one of my lists this way and it went from a 30 plus click through/open rate to a less than 10%. Gave it 3 weeks and went back to full HTML. Open rates rose again!
Makes me wonder were the open rates "fake" as in, if the message was displayed on their PC in the view window before deleting without reading, it was a false reading! Just not sure but have stuck with full ezine since then.
Then again, tried this way with my OrangeBeetle ezine and rates although didnt rise, they never fell.
Here is a point of interest though; although going away a little from topic. My ezine at
http://Hairee.com gets a rate of 30% plus open rate. My ezine at
http://orangebeetle.com gets a rate of nearly 100%.
Hairee is weekly. Orange Beetle is random. I wonder if more value is perceived on randon rather than weekly?