load_itempreset 0

bind f1 "load_itempreset 0"
it will load your first loadout

Refreshing critheals only works if you change class iirc

I remember nursey mentioning in a stream that a loadout switch refreshes your crit heals. You don't need to do the change class thing. It will refresh your crit heals, but it's not as efficient as a loadout preset bind.

=

for some reason the loadout switch bind sometimes has quite a bit of delay whereas switching class is instant

also pretty sure that as a medic you can back spawn while retaining ubercharge (like if you changed your hat) which is against the rules as far as I know (maybe not in etf2l)

on certain maps it can be somewhat useful for engi because it refills your ammo without killing your gun (on gully for example where the resup cabinet is all the way in the back of spawn it's way faster to use the loadout switch bind)
on badlands and snakewater it can spawn you on the opposite side sometimes which is problematic
a high tier meme that it allows is you to spam cow mangler alt fire shots from spawn
for example on badlands last you can sit inside spawn and ignite anyone who tries to push bottom left (if they send two soldiers bottom left to try and sync the ceiling you already have your finger on the respawn key so you can just teleport away if you are quick enough at reacting, only problem is a scout can slip through cause you're not actually watching the door half the time)
or on snakewater you can prefire drop down/shudder where they're pushing and hope to meme somebody and if it does move you to right side you just get crit heals and a full clip/health so there's like no downside

to explain the class switching there are a few ways to do it but I think the easiest way is just to have in each class config a key bound to +respawn which goes to a random class and -respawn goes back to the class you switched from
so when you hit the key it swaps you to the other class instantly and then upon releasing it you switch back to the first class (useful for forward spawning cause you just hold it down till the control point has been captured)
not on my pc arm so can't paste the exact code

alternatively you could just do it manually by hitting comma and a number key (or bind the number pad keys to swap to classes to avoid having to hit comma)

i was watching a seagull demo review from a year or two ago and he was like yeah it's probably one of the most under utilized scripts in tf2 no idea why anyone doesn't use it

that's actually pretty good

Using a loadout switch is in theory a lot worse than class switching because it has to reach the item server, find your loadout, and then it will respawn you with those items. So if the item servers are being bad or are down entirely it won't work properly. Item servers go down a lot and then you just straight up can't use the bind.