Here's my 2 cents. If there is any way you can store two bikes, I would keep your road bike and add a LHT. If not, then get a sport touring bike like a Salsa Casseroll, Soma ES, etc. I can keep up just fine on "B" group rides -- eg, 17-18 mph average -- on my Bob Jackson World Tour if I remove the rack, large seatbag, head and tail-lights and other gear that make it a great commuter. However, it's a pain removing all that gear (and replacing it later) just for a single long group ride on the weekends. So I generally leave my touring bike set up for commuting and ride one of my other road bikes on group rides. IMHO, if you ride a lot you need two functioning bikes anyway so you have something to ride when one of them is getting worked on, gets a flat at the last minute before leaving the house, breaks a spoke, etc.