I'm not sure all the "messenger" versions are from the pre-RD2 mold, that doesn't jive with the Sugino web site and some retailers I've seen.

The issue with RD2's is that the chainline is 45mm in the outer position when used with a 103 bottom bracket. Bottom brackets basically don't come any narrower than that, so the only way to use these cranks is to put the chainring in the inner position and run something like a 107 bottom bracket with maybe a mm or 2 of drive side spacers depending on how wide your cog/hub setup is and whether you're using their 1/8" rings (they're pretty thick, so moving them from outer to inner gives you like a 6.5mm change rather than the normal 5mm road double gap).

Some people think the 45mm chainline is no big deal, and run it as is. A Surly rep came on here a few weeks back and declared it to be "within specifications" if you run 8 speed chain. This is kind of a canard, as almost all 3/32" chain is 8 speed chain, while there's no such thing as 8 speed 1/8" chain, and the stock rings are 1/8". The messenger ring does come in 3/32", not sure if you get a choice if you buy the messenger crankset. Anyway, a 45mm chainline will work, but it will be loud and you will wear stuff out a little faster.

The XD is a very good crank, definitely as good as the RD which is to say good enough for anyone but hardcore track racers, and takes a normal bottom bracket (107mm JIS), but it's 110 so there aren't "track specific" chainrings for it. There are still plenty of options, though. The XD is a little hard to find in silver (except for the triple version, which probably won't work for SS because of the granny ring mounts), but the black ones are everywhere.

One off the peg option without going overkill (75's, Stronglight, Miche, Paul, etc...) is the new crank Ben's and Soma are doing, Ben's calls it Andel and Soma is selling it as their own. It's allegedly pretty good, and if you get the Ben's version it's under $100 with a chainring. It takes 144 rings, though, which are more available than they used to be, but still aren't as easy to get as 130 or 110. If I were building a bike today I'd probably shoot for a 130 square taper double from shimano or FSA, there are a million of these around now that people want 110 compact doubles and exotic bottom brackets, and you're never not going to be able to get good 130 chainrings. They're also probably going to come with a pretty good 42t ring, just get short stack bolts, move it to the outside, and you're golden. I prefer smaller chainrings whenever possible because you can use Dura Ace cogs, which are cheap, good, and easy to find.

There are a few other options of course, Pake, IRO, and some others. I don't know too much about any of them, and some are probably the same thing, the big issue is whether they come with a good, round chainring, or if you're going to need to drop another $30-50 to make them work well.