Well, finally got my Flex-1500, VAC and WSPR software working togetther (TX/RX/PTT and CAT). Had to setup the CAT as a Kenwood TS50 to get that to work.
Amazingly, my indoor magnetic loop antenna is doing a very good job for TX/RX with the 4m of #10 wire and MFJ-933. Will have to try the home made 12.5mm 3m copper tubing and coax capacitor tuning stub to see which one performs better. Since both are side by side, it's easy to switch between the two and make fairly comparative tests.