But then you (usually) lose sdcard support because manufacturer too cheap to give you a dedicated sdcard slot.

I don't recall that having been an issue with the phones I've had, but I guess it must be an issue, as doing a search for "dual sim" on Aliexpress now brings up a ton of adapters to let you use both dual sim and a sdcard at the same time... (though I can't say I'd like to have one hanging out of the side of my phone...