The Rolleiflex T comes in type 1 (grey leatherette) and type 2 (black leatherette) versions.
Type 1 is able to make images in 6x6cm format as standard, or with the additional Rollei kit in 4x5.5cm (not 6x45) or 4x4cm (superslide) formats.
Type 2 (the last commercial version known as the white face) can do the above but also shoot 24x36mm on 35mm film using the Rolleikin kit. This effectively turns the 75mm Tessar into a head-and-shoulders portrait lens.
The 75mm Tessar in the 'T' used Lanthanum glass in the lens elements as an improvement on previous Zeiss Tessar designs.
I have a Type 1 'T' and bought it specifically to make 4x5.5cm as well as 6x6cm images. The difference in quality between 4x5.5cm and 6x45cm is negligible in enlargements.
It's a fine camera and I really like the image quality from the Tessar lens.
Hope you enjoy your camera.
As a user, I've never understood the attraction of the T model, because it feels like a step down from a Rolleiflex Automat. But sometimes logic doesn't drive the market.
By the way, you got a great deal in the swap. Any Rolleiflex will always be memorable. A DSLR is forgettable as soon as the next model is released. Most digital cameras depreciate faster than a new car that's been driven off of the dealer's lot.
I actually ask Harry Fleenor on how good the T model Rollei's before I committed the CLA for mine. He said it's a consumer camera. The transport and inner workings is less robust than the pro models. He also went to say if you plan on running hundreds of rolls through it a week. It might not keep up. But who now days runs hundreds of rolls through a camera these days. I'll tell you since I got it back from him, I haven't had one hick up. The image quality is increadible as everyone is saying.