FWIW. I think that you need to consider WHY you are considering a different frame ....
Perhaps a strong consideration for YOUR decision may be based on the HEAD TUBE ANGLE because it will have some impact on how the bike handles at different speeds ...
[INDENT]The slightly steeper angle may feel more nimble at comparatively slower speeds (whatever THAT means!) ....
[INDENT]But, the slightly longer wheelbase may offset THAT sensation ...[/INDENT]
The slightly slacker angle may feel more stable at comparatively faster speeds if all other things were equal.
[/INDENT]
Compare the angles on your current frame's head tube AND decide if you want the same or a slightly different feel to how your next bike may-or-may-not handle.
Of course, SOME of your decision can be based on your aesthetic sensibilities AND your actual flexibility + preferred riding position ...
[INDENT]
IF you PREFER that your bike's appearance includes a lot of exposed seatpost, then choose the smaller of the two frames ...
BUT, if your current stem-and-handlebar are level with OR only an inch-or-so lower than the top of your saddle, then you should probably get the larger (i.e., Medium) frame & use a slightly shorter stem ...
[INDENT]If your current stem-and-handlebar are above the top of the saddle, then you definitely want the slightly larger frame, IMO.[/INDENT]
If you prefer to set up your bike with your stem-and-handlebar closer to 4" (or, more!) below the top of your saddle, then you should probably choose the smaller of the two sizes.
[INDENT]Someone I know who is apparently 6'1" races on a SMALL Road frame!![/INDENT][/INDENT]
NOW, presuming that you're generally happy with how your LOOK frame handles, then if you really just want a different appearance to the bike you're riding, then just consider getting-and-using some Campagnolo components!!! 🙂
[INDENT]A significantly less expensive option which I have read that other people have suggested is to simply change the color of your handlebar tape.
[/INDENT]
BTW. Whenever in doubt, choose a Pinarello or Colnago AND restart the thought process from the beginning.