Wait a bit and pick up a TTR when they become available. A few have come up on here lately.
They pretty much have the best of both worlds. They have the MFR reg so no fiddling to get the bottle on and off like the mk1 and mk2. They have an adjustable stock and a rail so you can easily add bipods or slings without drilling the limited front end woodwork on rapids.
The Mk4 trigger in the MFR/TTR is very good and the scaloped block makes loading easier if you arent using a mag.
The 280cc bottle is adequate for over 100+ shots in sub 12 (mine runs at 11.2 and i easily clear 100 before i get close to reg pressure) even at FAC if you halved that, do you need more than 50 shots at 20 odd Ft lbs? depends what power you are after i guess?
I loved my HW100. It was stunningly accurate. But, if anything went wrong, which yes its rare, but can happen, then it was a lot harder to work on than the Rapid which you can disassemble, re seal, tune and smooth out, and be back in the field within a few hours.
Hope this may help?
Regards,
Rhys
Theoben TTR1 .177, Steven B Blue/Grey Laminate Stock, Nutshot Mod, Hawke Sidewinder 10x42 Tac IR
Daystate Pulsar. 177, Donny FL Sumo Mod, Pard NV008LRF