>If nothing else it would be completely different than exploring Mars
Which is likely why it hasn't been done. If it's something completely different, it takes more time and money to get it working. Starting from nothing, exploring Mars and exploring Venus might both cost $100b. But if the research has already been done to research Mars exploration, sending another probe there might only cost $2b, whereas Venus still costs $100b.
No doubt you are correct in that assessment. Time to fire up Kerbel to see how much payload a Falcon 9 Heavy can get into an Earth/Venus transfer orbit :-)
Which is likely why it hasn't been done. If it's something completely different, it takes more time and money to get it working. Starting from nothing, exploring Mars and exploring Venus might both cost $100b. But if the research has already been done to research Mars exploration, sending another probe there might only cost $2b, whereas Venus still costs $100b.