Sam glad to hear that you're planning the Passport SE
I am not sure if you've seen the device in person, if you've seen you may fall in love with the Form Factor, The device build quality is up to the mark.
Now back to your questions.
Screen lifting issue is solved way back, I've had 3 passport and none had this issue.
Device tends to get hot only when you've revving the processor like streaming online videos or if your throwing some heavy task on it, howver if your usage is fair you may barely notice, name 1 device that does not heat.
The battery backup is amazing I can easily get with the device for about 2.5 days with moderate usage and emails.
Below is my 3 days back stats.
Attachment 412406
Now if you're installing Google apps or Google Playstore you may see slight lags or battery drain during standby, however if you don't have any of this then every thing is like Makhan.
I usually at times don't even remember when I had last re booted the device.
No app crashes or lags or hanging issue.
I am not saying all this because I am a die hard fan, my previous device was a Note 5 I sold it and bought a BlackBerry Passport OG I liked it so much I bought a Red limited edition and now responding to your query from a Silver Edition.
The downside Os BlackBerry Passport are
Lack of app updates and support
Pathetic Front Facing Camera
Back camera at times struggles to focus when it's a moving subject, howver the still are really good in 2016
No BlackBerry warranty.
BlackBerry Passport the productive workhorse.