I'll add a current datapoint for Rome Shuttle Limousine noted in the wiki. We had a generally good experience with them. The website can be a bit finicky so if you do not get an automated response to your booking request asking you to 'Accept' or 'Reject' the booking, it means the web form you filled has likely not made it to the company's office. As expected, we paid 50 Euros into Rome (Mercedes minivan) and 45 Euros back (Mercedes E sedan). Drivers were on time and professional. Even though we had requested to pay via credit card, the drivers strongly preferred a cash payment, which was no issue for us but a heads up to any FTers that may be future customers?

Thanks to those who contributed to the wiki on this. ^