I have the older vertical bobbin 2170. I've tried the newer Pfaffs and some of them do work pretty much the same.
The IDT is good, hopefully Pfaff improved buttonholes, it's a lot roomier than my 2170.
That said, the best thing for you to do is take your easiest and most difficult sewing samples to the dealer, sit there and play with the machine. Get most of your questions answered if you have difficulty with your samples.
I am not a fan of drop-in bobbins. It's far easier to cut threads from the underside of a mess up to get the fabric out from under the foot or an embroidery jam. However, you are the one that wants the machine, so you will have to decide.
There are some things you just have to try. I found out about size on serger feet the hard way. The sergers with the smallest feet were the Babylock Imagine and the Elna 704. The other sergers I tried were good machines - I just couldn't grok them. This is where you WILL have to decide.
Pfaff, Viking and Bernina have a foot for just about everything. So you might want to check out those, too.