Dunno about the particular boot you wanna use, but I've used issue USMC steel toe boots (Belleville 551ST). I think they were still lighter than the old leather CF boots.
You can wear them outside of games to get used to them: if you're always wearing sneakers (without much running) and you play once a month and run with boots, you'll feel a major difference, steel toe or not.
Otherwise, maybe your legs will hurt the next day. Maybe a lot if you really aren't in shape. Put some heat rub on em, take a couple Advil and you'll get over it. And you'll eventually build up endurance. Then you'll realize you're in better physical condition than when you started playing, and you'll be happy with yourself. It's win-win.