i'll throw my two cents in as ive been loading 38/357 for just about a year now, using the same setup you have.
I personally run a ton of 38 through my 357 and switching back and forth to magnum isn't a big deal at all. I usually back out the expander/powder charging die two full turns, run a case through and slightly adjust until I get minimal flare that will still bring the autodisk all the way forwards to drop the powder. then I take the empty case to the seating die, back the die out two turns , then back in until it firmly touches the case mouth and give it another 1/8 turn after that for a slight crimp. then I back out the seater a good bit as im going to use different bullets. When I go to load the first 357, i will have to do some minor depth adjustments being careful to not fully pull down on the lever to crimp it. once im near my desired oal, ill crimp it, make sure its where i want it and set it aside for a plinking round as i'll usually have to set it in a few more thousandths. seems like a lot, but it takes all of 3 minutes to adjust.
I load about 800 38's a month and prefer them because A- they're everywhere for grabs at my range, B- they are not nearly as difficult to run through the sizing/decapping die as magnum cases are.
I usually wait til i have 800 casings tumbled, primed and ready to roll before i do a run on the press. my method on the lee turret is quick enough that i can load the 800 in under two hours at a faily leasurely rate. I fill the hopper with hp-38(or win231) powder with the .32 disk such that it throws a 3.35gr charge. put a case in the shell holder, charge the case as i grab a bullet with my left hand, bring the case all the way down so its seated snugly and place the bullet. with my right hand still on the lever, i rotate the turret with it to the seating die, seat the bullet as i grab a new case. use the empty case to push the loaded one in my hand and place the empty in the shell holder, put the loaded round in a tray as i turn the turret with my right hand and repeat the process. once you get it down, you can load a box in 5 minutes flat. And no, this is not wrecklessly fast, im still watching the powder being dropped, reassuring there arent double charges etc etc.