Quoting ladykickboxer23:" Some bottles look nice and claim to have the latest technology but can be incredibly hard to use and ... [snip!] ... to have some gas with any bottle, just be sure to burp them. Burp them halfway thru a bottle and at the end twice if possible."
Yeah I agree. The drop-ins are good and i like them as my second choice but like you said they leak if not closed good and you can't use a bottle warmer for them..They must be placed in very warm water...to heat. and that sucks when you are in a rush.