3 arcseconds per pixel is something I can only dream about as the Pentax lens offers about 11 arcseconds per pixel with the ML16803. A 400mm focal length f/4 might be on the cards in a few years time when I've saved up a lot of pennies but I think I'll have more than enough imaging to be getting on with with the current Pentax lens and the TEC 140 for a long while. By the way, as I write FLI currently have a picture of my setup on panel 6 of the flash animation at the top of their website's index page
Even if the forecast is accurate we've had so much rain here today that I worry that it'll get foggy locally if the skies do clear.
Good luck to you as well.