I've owned a Rolleiflex 3.5E2 since 1966. Also two Rolleiflex Ts which I bought in the 1990s. I also recently acquired an as new 2.8E2. So Rolleis are in my blood, it seems.
There is a noticeable difference in weight and size between the 3.5s and the 2.8s, but they are not impossibly heavy or bulky. Using a 2.8 just takes a bit of mental adjustment. Accessories are (usually) somewhat cheaper for the 3.5 than the 2.8. Cheapest of all are the bayonet I accessories for the Ts, as this was the standard size for Rolleis from the 1930s and there are tonnes of bits available on the used market for this model.
To repeat myself from previous posts, the T allows you to shoot 16 exposures with an accessory slip-in '16' kit. The Rolleicords from model IV upwards also allows 16 and 24 with two kids (the 16 kit for the 'cord is different from that for the T). All Rolleis can also be adapted to shoot 35mm film.
True, the Rollei lacks interchangeable lenses, so what? I've shot with Mamiya TLRs, and at my age I wouldn't want to have to carry one on a hilll trek, they are like bricks. They give lovely results, tho. Not quite as good as the Rolleis, I reckon, but then with four 'flexes in my camera cabinet at home, I would say this, wouldn't I?
RolleiflexIBILITY, or what?
It is widely held that the Es were an early version of the later Fs (there was an earlier F, without the removable waist level finder, dating back to the mid 1950s). I've read and read and read some more about the Rolleis but cannot find any evidence to support this. What I do know, is that results from my 3.5E2 and my newly acquired 2.8E2 are virtually the same. I THINK the 2.8 gives me slightly sharper images, but as I have yet to put this to the test and enlarge shots of the same subject taken on the same film with the two cameras, I will say no more. This really isn't important to me anyway.
Rollei 'mechanicals' are very reliable. Unlike the electronic kiddy toys being sold nowadays, they go on shooting forever and then some. While film is being manufactured, the Rolleis will go on delivering the goods. Servicing is easy, if not exactly cheap, but then what camera can be professionally serviced cheaply nowadays?
The Rollei meters after they become "deceased" can easily be disconnected by opening up the top panel (the name plate) and disconnecting a linking wire. These meters always erred on the side of overexposure in bright sun or underexposure at all other times, so they were never reliable for precise shooting anyway. Almost every Rollei owner I know has a Gossen meter, which says it all...
Rolleis are the ideal minimalist camera but shooting with a TLR is an entirely different experience from using most other formats. My T images are sharper and enlarge better than most of my 35mm shots but the differnce between a 645 image taken with a T and a full size 6x6 image from a 3.5 or 2.8 with either the Planar or the Xenotar lens, is phenomenal. Not to say the latter two lenses are far better than the T's Tessar (well, they are, but the difference is not wildly critical), but most users I know say they like the T for its "character" while the Planar and Xenotar blow everything else out of the water for sharpness and mid tones. So this is all a matter of preference, really - and budget.
Any Rollei ('flex or 'cord) in good operating condition, will produce superb results. This to me is the sweetest icing on the cake.