Just from my current experience as a guild hansel with formerly 30 guilds (now 27), the notion that SoS drops your plunder is wrong. I have been replacing my lowland guilds one by one with SoSs, and my attack plunder has consistently risen as has my EB end bonus. Each time I replaced, my troop attack plunder goes up by roughly 440 000. I'm not sure if this is the most efficient method, but contrary to popular belief it is not negative for your money. I'm earning 19.58 mil per troop attack on the Haunting, 1.4 mil more than before I placed down my three SoSs. On the other hand, I've so far noticed that the guild hansels who loose money from adding SoSs tend to have other troop buildings around that is a great part of their stats- the two that I've seen tell me that they loose money happen to have between 200-300K combined troop stats, and I'm assuming pre-castle. In my case, I only have a tier 1 stable with no real important troop buildings, and my other 120K combined troop stats come from my castle. I suppose that the SoS doesn't like big troop buildings or more than one troop building, so be aware if you're this type of hansel.
If you are going to convert do it ALL in one, don't half ass it and go 150k 150k 2m 2m. I recommend saving 2-3T min before converting, ally trading will give you a nice boost too.
Lmao @ SOS doesn't drop plunder. All my lowlands are SOS and I have a GH alt , GH alt makes 24 mil I make 20 mil. So yes, GH make more and plunder drops by A LOT. That's why banks are chosen as GH (mostly) I've done this conversion over 3 times already, SOS drop plunder so if you can , go with the highlands vol's before lowland SOS . Soon as you put those SOS, you'll see the difference..
If you're going to convert, save up enough gold to convert all of your highlands to level 1 vol, then you can replace your lowlands with SOS without any plunder problems. Don't touch lowlands until then.
Oh, and to answer op, do option 1 until you get up to the 200b lands, THEN convert highlands to level 1 Vol in one big switch, then do your lowlands however b you see fit.
Today, I switched from 23sos / 20 vol, to 23guild / 20vol, guess what... -2m troop plunder, no noticeable bonus loss or gain. Draw what conclusions from that you want, ill be rebuilding my SOS asap
You have to be full GH, of course when you have one bigger it'll change. Try full GH and see what conclusion you get from that.