The RAZR is about as slow as you could get. It's GPRS class 10, which has a maxumum practical speed of around 5 KB/second. It sells on style, not on the specs. Your current v551 is EDGE class 4, with speeds up to 15 KB/s.
The fastest available speed is EDGE class 10, which permits up to 22 KB/s depending on signal and network conditions. This class of EDGE is found in the Motorola v360, Palm Treo 650, and others. You might check PhoneScoop.com's specs lists and phone finder to narrow down your candidates. The Moto v360 would be the closest to your existing phone in terms of style and interface, as well as having significantly increased battery life. You might want to look at that one particularly.
http://www.phonescoop.com/phones/finder.php
http://www.phonescoop.com/phones/phone.php?p=688
If I may ask, what's wrong with your v551?