The MX’s are heavier than the L with the most notable difference (IMO) being loader capacity. Depending on what you’re doing, the extra loader capacity may or may not be a big deal. Same with weight. In general, a heavier tractor will lift and pull more. A lighter tractor is easier on ground you prefer not to damage (grass, dirt trails, etc.). A smaller tractor fits in smaller spaces than a bigger tractor (sounds obvious but in my case that’s why I have the L instead of a MX). 3 point lift capacity (IIRC) doesn’t vary much with those models. For PTO implements such as chipper, generator, brush hog, tiller; the weight difference in those models matters little to none. In general the bigger the tractor, the more the tractor costs and the more the appropriate size implements cost.
Once in a while when I’m pushing the limits of the loader or drawbar pull on my L4701 I think I should have bought the MX5400 that was sitting beside it at the dealer lot. Then I get to bush hogging the field with a few dozen trees planted in a 12’ grid or working in some cramped spot down in the woods or coming up one of the narrow side sloped trails out of the hollow and am reminded why I didn’t buy a bigger machine. Also, have been pleasantly surprised at how gently the L4701 on R4’s treats our steep dirt trails. Recently brought an oak tree back from the creek bottom in 7’ sections with the grapple. If I’d done that with one of our older 2WD R1 shod machines pulling the trailer I’d be fixing damage to the trail after. No repairs necessary after using the L even though it’s a heavier machine.
I’ve heard it said the L4701 has a lot of HP compared to its weight. Probably not an inaccurate statement. I run a chipper, bush hog, and generator. PTO HP over 30 HP is a big deal for me. Pulling 4 moldboard plows is not on my list of chores so weight wasn’t as important a factor. Stacking 2000lb hay bales isn’t on my chore list either, so I didn’t need the extra loader capacity.
Once in a while in these type forums someone will recommend against the L4701 because it’s an “orphan” as there aren’t multiple variants on that frame. Honestly, if that’s the way you make decisions on machinery purchases there’s no help for you,
They’re all solid machines. Not like there’s a “bad” choice there. Just depends on what you plan to do with it.