As a newcomer to BMW and this site, I see there's a fair amount of discussion on lowering and un-lowering the RT, as it's a bit tall for some of us in the 30"-and-under-inseam club. I hope this post is useful to others who are interested in lowering the RT a bit.

I replaced the stock seat with a Corbin low seat, and I just had MrBeemer in Willow Springs, NC replace the stock shock springs with Hyperpro progressive springs from EPM performance, which springs increase the sag and have the effect of lowering the bike a bit more than an inch at rest.

The result is the bike fits me much better, and the change has not changed the handling characteristics noticeably, at least in commuter-type riding. In my case, my stock sidestand works okay on level ground, although I will have it shortened a bit.

From what I've been able to read, changing to shorter shocks does change the handling characteristics of the bike, and in particular the fork rake. I'd invite those with experience in that regard to comment, in the interest of informing people interested in the topic.

The points I'd like to make are these:
Having this RT fit me better makes me more comfortable and confident. I'm glad I made the changes.
The Hyperpro spring retrofit lowered the bike a bit--30mm, or about 1.2"--without messing up its handling.
Replacing the springs is more of a job than replacing the shocks with the springs still on them! I found that this is an even more difficult job if the bike has ESA, which mine does, so if you want do this, before you buy the springs, find someone with the expertise and equipment to do this job; not everyone, and not every dealer, can. EPM does offer a service whereby you can send your shocks to them and they will replace the springs and ship them back.
Since I still have the stock seat and stock springs, as well as a spare stock sidestand I found on ebay for $35, it will be relatively easy for a taller rider to return it to stock, should that need arise.

I have posted links to EPM and MrBeemer below, for those interested. Contacts are Klaus at EPM, Jon at MrBeemer.