Guts,id have no real problem doing the Duo one for s-video/component,but what you would need to purchase a encoder for this from Jrok and some panel mount jacks. Before doing so,email him asking about what additionally needs to be added to the encoder to get it to work perfectly with the TurboDuo. I remember there being issues about the video sync line or something maybe,so he would need to clarify this and the fix. I know he sells a sync cleaner thing for 10 bucks extra,and that does wonders for helping getting certain arcade game boards to sync correctly on certain tvs. I already know where to tap the needed RGB from the HUC6260A on the Duo,so as I said,just need the other info clarified from Jrok.
As far as Genesis decks go,the same applies. I can do a s-video mod on a Genesis 2 deck for sure if it is a MK-1451 deck,and a Genesis 3 any type of deck. This is actually a very easy mod and does not require me to build a amp or anything,just a couple of caps,and resistors,and some panel mount jacks. Older genesis one decks,yea,more likely then not if they are from the first couple of releases,as long as they have the Sony 1145 chip. However,really I detest the Genesis 1 S-video mod,its,to me,not up to par with the quality gained from the Genesis 2 MK-1451 and Genesis 3 decks quality. I think Black Tiger is looking around right now for a MK-1451 deck or a Genesis 3 for me to mod.
My Genesis I use is a Mk-1451. I don't play it all the time,but when I want to just sit and play Streets of Rage 2,or my jp cart of Strider,its great. I had a Genesis 3 deck modded but sold it on ebay since I did not need 2 of them.
As far as prices,as long as you cover parts prices and shipping back and forth,I would charge prob $15 for the Duo mod,and for the Genesis 2 Mk-1451 or Genesis 3 $10 for sure. Genesis 1 deck I guess I would do,however I am not eager to do so. On it I would charge around $20.00. Seriously though,if your dead on wanting the best image quality out of the Genesis s-video wise,go for a MK-1451 or Genesis 3. They use the better Sony CX1645 chip.