Having managed to get ggnfs compiled I compared it's speed with NFSX (ubasic/assembler NFS implementation written by Yuji Kida).
Test case 10^151+1 with small factors removed by ECM.
Elapsed time for NFSX: nearly 5 days.
Elapsed time for ggnfs: 13 hours 35 minutes. (Running factLat.pl, I'd not got msieve working when I did this test.)
Note this wasn't on the same CPU, NFSX was running under freedos on a 3Ghz box, ggnfs under openSUSE 10.3 on a 3.06 GHz box.
Other benefits are that factMsieve.pl can exploit multiple CPUs and ggnfs isn't restricted to degree 3 or 5 equations.
Chris (Very pleased with ggnfs)