Ahhh ... the age-old question. Ask this question in any ham club, and you'll receive many differing answers!
The main point of my presentations is to show fellow hams that they just might already have the necessary equipment to work the FM satellites: a handheld radio capable of "split freqs" (where it can TX on 2M and RX on 440), and an antenna improvement to that radio.
There's only one true, full-duplex radio on the market right now ... but, unfortunately, that Alinco model suffers some sub-band sensitivity problems. Whether or not it can be cured with future firmware releases is unknown.
A definition is in order: true "full duplex" means that one can monitor one band while keying the mic on another. The Kenwood TH-F6a, for example, is a dual-receive unit with its independent VFOs - but not true "full duplex," as you cannot monitor anything while the PT is pressed.
SO ... What are you using? Icom's IC-W32a? Yaesu's little VX-3R? My current favorite HT for sat work - the Yaesu FT-60R?