The notion that chain armor restricts and weighs less than plate armor is common in any kind of medieval or fantasy game, but it's false and I don't understand why it persists (other than addle-brained reasons like 'balance' or 'fairness'). Hell, AD&D's Unearthed Arcana pointed this out 30something years ago, quite properly plate offers more protection with less weight and encumrance than chain.
Chain armor puts most of the weight onto the shoulders, neck and waist (if a long coat is worn with a girdle or belt). Plate armor is largely self supporting. Both of them can cause balance problems in awkward positions and both restrict movement, but full chain armor is heavier, bulkier, moves/swings more (making the wearer's inertia less controllable). The improved flexibility of chain over plate is not as relevant as one thinks, since full plate armor has sophisticated joints and balancing built into it deliberately, something not even possible with chain armor. Plate armor is hotter to wear, but overall chain puts more strain on the wearer for extended use.
So, all in all, chain armor has the advantage of: less skill required to manufacture and repair (though it's actually more tedious), better heat dissipation, low cost (sometimes - in the mid-late renaissance nobody would be making full maille and you'd be paying novelty prices).
Plate Armor has the advantage in: every other area. Plate and chain hybrids are, likewise, superior in all the areas plate in though not so much as full plate.
It's something I noticed in Barbarians of Lemuria, too, and it's just not accurate to make plate more encumbering, slower, heavier or more difficult to perform skills in. It's not fair, but that's superior technology for you. Hell, all of this is true of the Roman 'banded' plate Segmentata v. Hamata, the only reason Hamata made a comeback was oversized armies, declining treasuries and a decline in the availability of skilled steel workers (plate requires laege blooms of metal).
Granted there is some ultra heavy plate armor, but unless your PC likes novelty equipment or semi-bulletproof gear that's not going to come up, and it would still be superior to the equivalentin chain.
A chain hauberk will be lighter than full plate, but it will also grant less protection than a breastplate and be heavier for the protection it affords.
Chain armor is going to be better for sneaking, crawling and climbing. Plate is better for running, jumping, fighting and any kind of acrobatics or cartwheels. Basically, if you are moving like a biped, plate is better. And with good reason, it's far more sophisticated, better metal, better designs, better craftsmen and much less overlapping material.
I suggest swapping the Burden, ENC and Physical skills penalty of Chain and Full Plate, then taking half-plate down to a -15%, since it is at least as maneuverable as Lameller, the latter being rather bulky and heavy because of overlapping pieces and swaddling leather/cloth that make up its backing.