Well, if you are use to 2 meter prints from 35mm film, then doing only 2 stitches from 4x5 is very convenient. You then get from 4x5 (after including overlap with stitching) either 4x9 or 5x7. However, you have one problem left...the scanner. An epson class scanner (4990, 750) are good to about 3-4x enlargement with high quality. So you won't get those 2 meter prints you want. If you shoot 8x10, you will get to 40 inches, and maybe that is enough. On the other hand, drum scanners (Howtek 4000 and 4500) have come done a lot in price (few thousand) and would give you enlargements of 10x or greater easily and solve your problem, but do you want to get into mounting stations, fumes, and scanning supplies? The advantage of sticking to 4x5 is ligher weight of camera and film holders, less bulk, and far greater choice of films.
Another choice is shoot 617, and scan with a Nikon 9000 scanner. Two stitches will get you 4x7 (with overlap). The Nikon scanner will easily get you to 2 meters and more. I consider this the most affordable approach, because buying into a system means you must think not just about the camera, but also the scanner. If you go the other route, and decide on a drum scanner, remember one thing.....one repair can set you back $5000 easily, so most people buy a spare one for parts. Is it worth the hassle? For 617 you have 2 types of styles.....617 view cameras (look at Shen Hao, Ebony), or panoramic cameras (like Fotoman, Goaersi, Widepan, Fuji, Technorama).
Some other advantages going this route are....carry a days supply of 120 film in your shirt pocket, no dust issues, need for film tent, easier to process, and total cost of film/lab is far less.
A third option (a 617 roll back for your 4x5), but there are issues with wide lenses.