Two part linear polyeurethanes are not as difficult to apply these days. I have rolled/tipped Detco/Sterling on a 28 foot sloop
with very good results.
Prep is CRITICAL. The high gloss of LPUs will accentuate any surface imperfections: pits, pinholes, scratches, etc. An owner a couple slips down from me did his deck in LPU without proper prep, and it looks REALLY BAD in bright sunlight. Applying extra coats of primer and using high build primers can really help in the prep depending on the surface condition.
Even with good prep, you need to pay attention to temperature and humidity to avoid the paint blushing.
I have heard Interlux Perfection is even easier to apply and is more forgiving.
One disadvangtage with LPUs: you cannot spot patch the coating very easily. You simply cant sand and 'feather' in a spot with spray or brush and have it not be noticeable.
I have been told by my yacht painter friend that the new acrylic marine
paints are easier to apply, easier to patch, and just as durable as LPUs. I am not sure you can brush acrylic
Regardless, if you are not willing to do the prep, then stick with a single part topside paint (like Interlux Brightsides) as it wont show off the surface imperfections as easily.