I'm a little late jumping into this situation, but I would say that you'd be doing yourself and your company a disservice by not investigating training. With the size of your department and projects on your plate, you will need serious migration planning - regardless of the path you take. Management needs to be informed of strengths/weaknesses of their choice as it relates to your plant. A "PLC may be a PLC", but it's a significant paradigm shift for you. You may want to phase training in, but push to send at least a few guys initially.
If it were someone asking to learn to program a PLC, or a one man shop prepared to get into a project, my answer would be different. Consider putting a "working group" together or doing a "proof of concept" to relate your experiences and a clear picture of the total cost of ownership.