Hi Mike

The best way that I can think of describing the difference between the two units you have mentioned is to liken them to cars. Do you want a nice smooth ride in a luxury sedan, or scoot around in a little compact economy car? Olympia typewriters are described by many as being the Mercedes Benz of typewriters. If you have the desk room and want to get into some serious typing, I would definitely lean towards the SM-9 for an honest true typing experience.

If you're looking for home typing, you can type page after page on a well tuned SM-9 and your hands won't get tired. However, if you're looking for a handy little typewriter to stash in the car so you always have one with you to type out a page or two, the Rocket will serve you well. My hands get tired far more quickly when using my Rocket than when using my SM-9. Other members here may have different preferences, but we are all different people and no one machine is the right machine for everyone. Hope this gives you a starting point, and let's celebrate our differences. All the best,

Sky

Any comparison between an ultra-portable such as the Baby (Rocket), and a full-size portable is likely to end up in a description of a more luxurious experience coming from the bigger machine. As Sky pointed out, the ultra is a more compact, travel-friendly model that is handy for typing out a quick letter. The full-size model will serve better for longer, more frequent typing sessions.

You might already be aware of this fundamental difference. Your Smith-Corona Super Silent is a premium portable, but I'm not familiar with the Consul "225". I own a 224 (a full-size portable), and a 235 (ultra-portable), but don't recall having come across a 225.  

Both the Baby and the SM spanned more than one design generation, so I think it's equally important to consider your aesthetic preference when planning your next typewriter. If you like clean, more modern lines, then yes, a newer Baby and SM model (like a SM8 or SM9) would be worth looking at. Personally, I prefer samples from the golden age - and in particular the feel of a key-cushioned older SM.

The Silent Super WAS produced as a direct competitor to the Olympia SM series as well as the top machine in every manufacturer's stable. One thing you must consider is that the work history of the individual machine and the level to which you service it is going to matter a great deal. I have a SC Silent from 1948 that is possibly the snappiest and fastest machine among my 11 typewriters. It can keep up with my computer speed touch typing over 65WPM, without typebars jamming. I also have two other SC super 5 samples, one a Silent Super, one a Sterling, and none of them come close to that Silent I mentioned. the reason i don't use it more is that it is a 10 CPI machine.
After that, I prefer my Facit TP1 to all of my other machines for long sessions of typing. For ME it's just perfect, though I really do love my 1949 Remington Noiseless Model 7. The Noiseless portables force a typing technique and rhythm which forces a person to have better form. It feels lovely and the lower impulse of typing is pleasant as well. 
I recently completely overhauled a nearly-unused 1966 SC Sterling (late Super 5 chassis) as a gift for my sister. It's a nice machine and I have gone through it almost to the level that it is sterile, but it simply doesn't type as nicely as my '48 Silent. It has almost zero wear as there are very few impressions on the anvil from keystrokes. This is as "new" a machine as I've ever owned. 
My Olympia SM9 DeLuxe wide carriage is a great machine, but it is simply an office instrument, in feeling. A wonderful typewriter to work on, but MY PERSONAL PREFERENCE and the history of the machine relegate it to the shelf more than working. One of the SM9s I've worked on for a customer worked well but just didn't feel great in spite of intense cleaning and overhaul, fresh rubber and zealous detailed lubing. So, the "Mercedes-Benz" of typewriters felt like it had worn out and flattened suspension bushings, and a lot of rust (I'm restoring my 1972 Mercedes 220D right now.)
The answer to all this is that you may have to try out multiple samples of a single machine to really find one that works for you.

Phil Forrest

In your typewriter-search travels, take a test drive on the Facit portable machines which were made in Sweden.

Here are some of mine...TP1, TP2, 1620, and ADDO...
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Whoa! Those Facets are very cool. What a beautiful family. I thought I could hold this hobby to 3 or 4 units but that might be impossible. I'll justify collecting as being cheaper than golf.