As far as the dome therm, they are what they are. Not sure if they are anymore accurate than the old style. I have the same style on my WSM. I use it as a gauge and my Thermapen to tell me what's going on. The lid holder is just like the Performer and does not come off. Well it does, if you want to remove 3 bolts every time you store it. It's a great grill. if you want a OTG then go for it. You'll be happy.
Actually I just looked it up and it still has the lid hanger. do you have a pic of one with the other lid holder.
2000 Weber Simpsons OTG
2010 22.5 WSM
Smokin' Bucky UDS
Early 70's Red Weber Statesman
1995 Red Weber Master Touch
2010 Brick Red Touch n' Go Performer