What is the difference between a dry sump vs wet sump? Any pros or cons with wet sump or maintenence issues?

I think the wet sump just robs more HP.

Dry sump has remote reservior and return with oil sprayers? The gears dont run in a bath of oil, just get sprayed with fresh cooler oil from the external sump?

Dry sumps have the oil reservoir in the lower unit. Dry holds about 4-5 quarts of Torco oil and the wet holds about 4-5 gallons of Merc HiPerf sterndrive (or similar) oil. Most of the wets had a reservoir inside the transom.
Dry sumps are more efficient.

Try searching dry sump in the forums: there's a lot of info already posted.
Due

prop rotation matters on a drysump as the prop shaft turns the oil pump,wrong rotation and you suck Air instead of pumping oil... a drive set up to run LH in foward must be run LH rotation.....or so I was told. I'm newer to these #6's but man are they built nice in side

those oil pump housings are pricy.

All #6s (wet or dry) are rotation sensitive.
Due

Thanks for the feedback......any issues with the wet sump #6 or are they pretty much bulletproof?

bulletproof...just like the dry-sump...same gears, minus the oil pump

If you are thinking about replacing you brovo's with 6's here are a couple of things to think about
The 6's will add about 700 lbs to the total weight of the boat and of course all the weight is in the back and may upset the balance, you will need to move the engines forward to make room for the trans or crash box, Props are 2X or 3X more expensive than brovo props. Power steering pumps and metering valves should be considered, spacers for 6's are more expensive that brovos when you are dialing this in, tie bar will have to be replaced, if the engine is moved forward tail pipes will have to be longer, sea strainers moved etc...

And new motor mounts....the rear has to be supported now. Bellhousings with coolers.....all new plumbing. It is a complete re-rig. but the result should be worth it if done correctly.