ok, this is the one to get, no question. Rarely (if ever) has a product totally exceeded all my expectations. The Pearl Izumi base layer has done just that.
Here's the scenario: 60-30°Florida winters (if there is such a thing), competitive bmx/ mtb racer/ strava dork, 6'2 180lbs (XL) perfect fit, long in the back to cover your lower back when riding, long arms for ape-like appendages, snug fit without restricting movement or looking like a superhero.
And the MOST AMAZING THING of all is the magical stink repellant, no idea how it works but it truly does. I'm a sweaty SOB and stink more than most but this shirt can handle it, if your not near a washer, just flip it inside out and let it air out....shazam no more pit funk in the morning.
Whatever you end up paying for this, it is worth it, I loaded up on them at the low point of one of the wild price fluctuations....
For 55° commuting use this and a light windbreaker thing (like P.I. elite or L.G. electra ..both darn good)
For 55° - 45° trail use (pegged, WFO, wide open, no lollygagging) use just this baselayer with no other shirt/jacket and you'll be dandy. When/if you stop, the cold will soak in but it'll warm right back up as soon as you get goin' again
Any colder than that use the above mentioned windbreaker/jacket or if down in the 30° range use a fleece (like a Marmot ) over the base layer and under the windbreaker.
gratuitous self promotion: When in central Florida be sure to visit Chuck Lennon trails (built in an old quarry, fast flowing singletrack, total tree canopy, and wide range of skill levels from trails the whole family can enjoy up to the rough stuff with 4-6' fast rollers/drops.