Nice machine, Shingo. I like the 2009 steam wand upgrade and ergonomic PF handle. Sweet.
Re: the original question of grinder to pair with Silvia:
- if espresso only, I would go with a used high end you might find on craigslist or eBay. Mazer Super Jolly (if you have the counter space), for example. Mazer Mini is also a good call, and Ascaso has a worm driven grinder, essentially for espresso only use, though there have been reports of chute-clogging. If you like worm-drives (for micro-adjustments), check out Compak, as well.
- if you prefer steps, for use in other brew methods, the Rocky might be the simplest, smartest choice. Having said that, take a look at the new Baratza Vario. Same price point as Rocky (give or take), with a unique step system and programmable timer with memory.
- if $ plays a large factor in decision making, and you can hold off on the urge to upgrade for a year or two, you cannot go wrong with the Baratza Virtuoso (reviewed in three parts on this site). Not as precise as the others, but certainly doable for espresso through to press pot.
The rule of thumb is generally spend more on the grinder than the espresso machine, but for many of us mortals, it is not immediately practical. But watch out for upgrade fever. You could be looking at a La Speziale Vivaldi II and Mazer before you know it!
I went with the Mazzer Mini for my Silvia and I find the grind to be excellent. I don't have experience with the Rocky so I can't give you a comparison though.
Only downsides I've found:
- Mazzer is quite high so it won't fit under a standard counter even with the smaller hopper on top.
- Step-less grinding is great for getting just what you want but it can make it hard to get right back to where you want after making changes rather than "2 clicks back" with a regular one.
- It is VERY quiet
- grinds consistently, without static clumping
- machine built very solid