I bought a new bike last year and went through something similar. All the test rides were nice but just not the same as my old bike.

I still have that old bike and brought it out this past winter. It felt strange, familiar yes, but I realized it was too small. After that ride I hopped on my new bike and it had that nice familiar feeling.

So your new bike will eventually become 'your bike' and Frankenstein will have its place as your old bike.

ps, go for the 7.5