Going from a J-frame to an LCR & back?

Yes, you're going to short-stroke the LCR doing that. I have, too.

But if the only DA revolver you shoot is an LCR you probably won't.

You're right about the LCR being bulkier than the J.

As for pocket carry, I've found the loaded, steel-framed LCR's (.327, .357. 9x19), being about 19 oz loaded, are at the max weight for pocket carry.