Religious arguments aside, the obstacle for TCP/IP performance over ATM has
been due to two factors, small buffers and no explicit flow control.
The new switches have large buffers. TCP works well with these switches.
Explicit flow control will allow more flexible bandwidth management. That
applies to TCP as well as ATM.
Check out the price of an ATM circuit (considering overhead, etc) and if you
perceive value for the BW then buy it. No apology needed, just purchase
orders. 
If you find that you prefer raw bandwidth over optical fiber
and lots of cisco interfaces, fine, but if you like network level switching,
shared network bandwidth and the price for that, buy switched services.
--Kent