I was wondering if anyone has used their 50 sized Shimano for fishing crankbaits. I have been considering using it on a M power cranking rod with 20lb braid to fish small squarebills, lipless baits, and DT-6s. Any input would be appreciated.

Yes

Yep. 1/4 oz Lipless all day. 

All my cranking, besides really deep 20+, uses the 51e's

I was amazed when I switched my cranking reel from a T3 1016, to chronarch ci4+, to a chronarch 51. I can cast lighter shad raps #5 well and also handle medium divers. I think you'll like it as long as you don't go over 12 feet diving cranks and stay under 3/4 oz cranks..give or take.

 

However later on I did add a longer 90mm handle and I think this helps getting more leverage.

Used to use my curado 51e's for 1/4oz lipless, dt-6's, dt-10's all day long. Now i use my core 51. They both work great.

I used to use mine for squarebills, lipless, and smaller divers like the SK series 3, etc....no problem. I'd still have them if I didn't get bored with them and moved on.

DT6 are pretty light cranks. The advantage of using the 50 reel is the spool is semi finesse. It can cast light lures a lot better than the 200 size spool.

I don't crank enough to justify couple setups so I have one MHM crank rod. I was having trouble casting shad rap #5 and sometimes 1.5's. IM sure it was more due to the MH rod as it doesn't load up as nice as a M rod but I didn't want to go a power down since I want the MH for banging squarebill and rip lipless off grass.

So the solution was using a 50 series. Now I can cast 3/16 shad raps respectfully and I can bomb 1.5 with no issues. Again this is with a GL2 MHM rod. I'm sure your MM rod will load up better but still the 50 will cast better than a 200 for those light cranks.