Yes there is a mind boggling array of different configurations - a few things to consider:
Yes "inside the can" might look kind of ugly, that's surely one reason for the can (and to protect whats inside). Each pair/each speaker is tested at least twice before it's sent out. You get a pretty long "in home trial". When somebody brought one of the cheaper old Ohm models to a DIY gathering listening event it was widely considered by the listeners to have better imaging than even the best/most expensive speakers that were auditioned.
Ultimately, what's most important is how do you like the sound of them in your listening room.
I worked at Ohm for a few years (not since 2003, except for occasional trips back to visit). My favorite current (my last visit was about a year ago) model is the 1000 for it's combination of size, overall sound quality, and bass output (relative to it's size). It's not the best model for a low power tube amp (I expect the largest models to have the highest sensitivity for that application, despite their larger "power rating" listed on their website).
DIY adventures may be successful - but it's going to require a lot more ingenuity (or luck) than a typical DIY box speaker design.
It is partially because of the wide variety of different configurations, even in the same model, over the last 30 - 35 years, that Ohm generally asks you to send back BOTH drivers when doing repairs or upgrades.
