Chris,
I'm looking for a really good, comfortable carry, easy to shoot.
Comfortable to carry often means uncomfortable to shoot with +P or Magnum loads.
My 649 is a newer model (w/lock) and it works fine. With .38 or .38 +P ammo it's fine to shoot. Using .357 Magnum rounds in 110gr and 125gr are definitely harder kicking but still manageable. The 158gr JHP .357 Mags, however, are distinctly rough on the wrists and hand. I should also mention that the noise generated by any of the Magnum loads is severe AND accompanied by a concussion wave you'll definitely notice indoors.
The 649 is the stainless steel gun while the 638 a stainless/alloy frame gun in .38 special only. The ultra-lightweight Titanium cylinder models run about 11.5 oz whereas a standard "Airweight" aluminum (or scandium) frame with a steel cylinder is between 14 and 15 oz. Generally speaking, shooting these guns with +P ammo
hurts due to their light weight. Additionally, older models like the Model 38 with aluminum frames can stretch out over time on a diet of hotter loads. Scandium guns seem to resist this problem much better.
Taurus makes a similar line of concealed hammer guns in their "CIA" or "Protector" lines. Ruger has bobbed the hammer on some of their SP101's too.
Unless you absolutely need to reduce the weight, I'd stay with the steel guns. Since your Firestorm also weighs 23oz, if it's weight didn't bother you the 649 shouldn't.
A new 649 should cost in the $650 range with a lightly used or like new used gun around $480 to $500. The 638 should run you $20-$30 less. For guns made with Titanium you can add another $200 to $300 to the price tag.
Holsters that fit the more popular 640/642 series should work for the 649. The only holster I've seen for these guns with a retention strap is from Bianchi however.
Speaking of holsters, Fobus and Houston Holsters both make a kydex holster for the Bersa/Firestorm pistols. Your Firestorm is actually made by Bersa and the major differences appear to be the shape of the triggerguard and the sights.
You might want to check out the
Bersa Thunder Chapterhouse for more info.