So I've had Hold Fasts for a bit over a week now. I usually ride exustar laminated doubles on my main bike. I've put at least 100mi on them. I don't do tricks (other than track stands and bw circles?). I ride fast, I cruise, I ride brakeless and I like to skid down hills. Here's my 2 cents:
Power Transfer
Toe straps > Hold fast. The width of the Hold Fast strap is pretty much the same as a double strap (although more material) so I'm not buying into the advantage in power transfer. If anything I would put toe straps ahead by a bit just because I can crank them down really tight in comparison.
Hold
Toe straps > Hold fast. Like I mentioned above, you can really crank down tight on toe straps on the go. Hold fast are more set and forget so I didn't expect them to hold as tight and that held true. I tried tightening Hold Fast on the go and it was a bit tougher since I had to pull and pat down the velcro at the same time. Even then, it just doesn't seem like you can get them as tight as toe straps which only need to be pulled. The wedge design is very good however. It does hold your foot fairly well and I didn't experience any slipping. I felt safe in them but toe straps give me that extra security. If you were to run both straps at the same "looseness", the Hold Fast would probably provide better hold because of the wedge design.
Ease of Entry
Toe Straps > Hold Fast. It may just be that I'm new to them, but occasionally it was harder to get my foot wedged properly in the Hold Fast because the material isn't completely rigid. I use steel clips and the rigidity helps keep the strap open for an easy entry. I don't see this as a real problem though. Just a couple extra seconds of wiggling your foot around to get proper placement.
Ease of Entry/Exit
Hold Fast > Toe Straps. Like Dinosaur88 mentioned, they are designed to get out of easily.
Comfort
Hold Fast > Toe Straps. Although Toe Clips/Straps are completely comfortable to me, steel clips can dig into thin shoes and cause some discomfort. Hold Fast straps are basically 1 big wide piece of nylon. They would be comfortable on bare feet.
Cost
I guess this depends on what you're comparing them to. Cheaper than pricey doubles like Toshi/MKS/Kashimax/Cadence but my Exustars were $40. Used them for 6+ months and they are holding up well. No slippage or stretching.
Pedal Compatibility
Toe Straps > Hold Fast. I put the Hold Fast on basic all-city track pedals and they were quite a pain to install (pliers required). It seems like almost any pedal that would work with double straps would work with Hold Fast straps but toe straps will fit just about any pedal and are easier to install.
BTW, I have GR-9s and I really do think you can rig Hold Fast straps on them if you use long bolts (where toe clips attach) to form a "slot" for straps to feed through. I already do this for my doubles but I'm not going to the trouble of installing them on the GR-9s to prove a point
Conclusion
I've haven't had the Hold Fast straps long enough to comment on durability but the construction is pretty solid. I wouldn't be surprised if they last quite long. But there are plenty of positive testimonials from trick riders that beat the crap out of them compared to me. In the end, I'm going back to toe straps/clips. Hold Fast would definitely be ideal for trick riders and adequate for commuters but they don't offer
me anything over toe straps/clips. They also look pretty ugly on most bikes, purely my opinion of course