I have an original SF 8X that puts out an incredible 110 lumens for almost 1 hour, and uses the B90 recharcheable battery sticks, just like the 9N series did. This is all aluminium, and very well built. I carry it in a Safariland black basketweave cop sheath that prevents the buttcap from being activated. Other additions were a stong lanyard that I keep on it for use with a pistol (Harris technique) and a red snap on filter.
They no longer make the exact 8X with the old 300 series 12 hour charger, but now make a plastic model and a new aluminium model the 8AX and the 8NX. Both are slightly larger than the 6P series of lights, but also don't use the more expensive lithium batteries. The also come with the new 2 hour B90 rapid charger, which is much better than the old charger. I recently upgraded to the new charger, and bought two new Ni-cad B90 Batteries, as after almost 8 years or so mine had worn out. As someone said, their customer service is excellent. On the bigger lights, about 6-7 inches in length like the 8 or 9 series, expect to replace the lamp assy. every 60-90 minutes of run time, at about $25 each. If you are just using it infrequently though for hi-intensity lighting situations, that is a long time between replacement lamps.
My next SF light will either be the Aviator, to stow in my flight bag, or more likely the new E2D (Executive series) Defender, with crennalated (sp) crown that can be used for striking. If I were you I would look into this exact model. It is small, compact, 65 lumens, and pretty good on the batteries, and is excellent for use with kubotan techniques if you know any of those.
FINALLY, my son just joined the police academy, and they specified new streamlight scorpions rechargeables for everyone. Nice light that comes in 2 models, with only the higher end one having a buttcap activator. Extremely bright and well worth looking into, about the same size as the SF 8 series.
Good luck!
Norm