I think it depends on the cat. Ferris is TERRIFIED of being put in a carrier, so I had to get a "top-loader" so I can literally drop him into it and slam the top shut. Trying to shove a resisting cat in through a side door turned out to be impossible.
Ginger, on the other hand, will walk right in through the side door with no fuss whatsoever. She's such a good girl.
The thing is, the new carrier is a "small" size, so I was thinking if I try to put her in via the top door, her legs would be on the floor of the carrier and she could possibly spring out in one fell swoop. If I use the side door (standing the carrier on its end) then there is a bit of a drop, making it a bit harder for her to spring out. I would definitely use the top door to get her out at the vets. Have any of you had difficulty putting her in via the top?
What I would do is get the cat used to the carrier before having to shove them in there for a vet call or something. I would keep it out in the living room for PHX to play in and put cat nip in there and his favorite toys. That way he will get used to being in there and it will smell like him. Then hopfully when I have to use it... he will already like being in there.. But every cat is different.
Which reminds me. I need to buy him a carrier. I don't even have one for him right now.. oops. When I bring him in my car- which is pretty much NEVER. He just lays down in my back seat and sleeps. Or he'll get in my back window and sleep- but I say NO PHX I CANT SEE! And plop he'll jump down into the back seat again. LOL. I swear they know english better then we think!