Research in Motion (RIMM) dazzled analysts at its Florida investors gathering with discussion of its business plans and a hands-on demonstration of its newest BlackBerry, once called Meteor and now known as Bold.

Analysts and investors came away from the event Monday reassured about the long-range growth prospects for RIM’s brand of e-mailing smartphones. And why not? BlackBerry’s secure, simple and sleek devices have won a favored spot on the belts of millions of hard-charging professionals.

But it is the short-term cost of the growth that gave a few analysts some reason to trim expectations in the wake of the meeting. RIM is expected to spend more on research and development as well as marketing this year as it defends itself against challengers in the smartphone sector.

“Our takeaway from the capital markets day is that RIM is clearly in ‘investment mode’ as management correctly sees a tremendous opportunity to take share from traditional handset vendors,” Morgan Keegan analyst Tavis McCourt wrote in a research note Tuesday.

“This may limit margin expansion near term, but substantial revenue and earnings growth should continue as RIM expands its product line and its marketing initiatives,” McCourt continued.

And though the company didn’t offer a date when Bold would start selling in with AT&T, the presentation materials provided by RIM put meaningful sales in “late summer/fall,” according to Pacific Crest analyst James Faucette.

This is later than the June debut originally expected and it gives Apple’s (AAPL) new 3G iPhone a two-month head start. The iPhone is expected out on June 27, near the anniversary of the original phone’s coming out party.

And as Apple tries to edge iPhone into RIM’s business-users domain, BlackBerry’s room for growth is in the lower-spending consumer crowd, with its Pearl and Curve. To analysts, this means more subscribers but smaller phone bills and therefore less revenue per user, a key measure of smartphone strength.

“The company pointed to faster [average revenue per user] erosion than we have modeled and indicated the possibility that margins may not be quite as strong as we have modeled,” writes Pacific Crest’s Faucette.

The tempered expectations offer a bit of a reality check as RIM enters a challenging second half of the year.