There are some fantastic dx machine portables. To name a few the Panasonic rf 2200, Sony 2010, Eton E1, several of the grundigs, the 800@650 and others. What do you actually gain by owning a tabletop boat anchor?

I have a Drake R8 that I got when they first came out, but about all I use it for is SSB at night and to catch Radio Australia in the morning.
My Sony 2010, as well as a couple Radio Shack versions of Sangean models I've picked up at yard sales, serve mostly as fancy FM receivers or AM DXers, or something to use when the power goes out.
The decline in international broadcasting has taken away a lot of the allure, but it's still more enjoyable to pick something out of the air as compared to online sources.
If I were starting out today, I'd probably stick with the 2010.

Take a look at the extra features of an Icom R75 and then take a look at the features of your RF2200 or Sony 2010.

With a tabletop, there are more 'tools' at your disposal -- more features that make it easier to pull difficult stations out of the mud -- pass band tuning, notch filters, more than one or two bandwidths, real noise blankers (that actually reduce or eliminate noise), etc.

You can DX with simple equipment, but you have to learn to work your equipment a lot more, and also know how to work within its limitations.

I was able to hear North Korea, Central America and Colombia one winter on Medium Wave with a boombox and a large loop antenna. It would have been a lot easier with an Icom or Drake, and with a tabletop I probably would have heard more DX stations than I did with my boombox setup.

Tabletops also generally have superior overall circuitry than your average SW portable.