I have been doing the exact same thing and I have recently bought a Mamiya C3. Its the older early sixties version of the TLR and its built like a tank. Its as clean as a whistle, really well looked after.
After researching these wonderful cameras now wish it had some of the features of the C330s. Although I love the design / build of the C3, the C330s makes far more sense photographically.
1. Interchangeable focus screens - perhaps you don't want to change them, but perhaps you would like to clean them, I know I do - it's very easy to do and the screen pops out, just like a DSLR. Saying that, some of the focusing screens are really quite poor, with heavy vignette - and lets not forget engrained dirt, so its another area you can 'mod' the camera if you are not happy.
2. The C330s viewfinder has a parallax error line visible in the top left corner, which descends as you closer focus. This shows where the top of the frame will be, so you can adjust for parallax errors between the view and capture lenses (top and bottom). Aim the camera at your subject and then lift up to read adjust for parallax. This is particularly useful with all lenses in the series I would imagine (I only have the 65mm), without it you could be chopping off heads - just like the good old days of gran behind the camera
3. Everyone say the build is not so good on the C330s and although that is true it's nothing to worry about. It's lighter and still robust unlike some modern digital cameras that we use without question. Its solid, firm in the hand and easy to use.
I would go with the C330 all the way, but I have to say I do enjoy the C3 immensely. The parallax errors only come into play at just over two metres with my 65mm lens so unless you are close focusing its not a big deal at all.
I just got my self the 'paramender' as I have been working on a series of flower closeups (what a brilliant macro camera this is) so thats the gadget to get if you need to ensure your vision aligned with the film!
David