I can understand wanting to trade up on your Roland as the sp540i runs the old Epson DX4 print heads which can be entertaining to align properly.
Personally I would be going for one of the later DX5 or DX6 printhead machines as their is less to go wrong and print speed and quality far surpasses what you can get now.
Also I would opt for two machines, one to print and one to cut as it can be very frustrating waiting for a printer to finish to get your already printed materials cut. In the long run this will make you more productive.
Their is also the option for latex machines but I have had little experience with these machines and from what my previous employer says about his it can have some serious down time and uses print heads (although cheap-er than solvent machines) at a much faster rate.
SC