Prior to the G5 HSI with autopilot interface capability I'd have leaned towards the Aspen, but now that the the GAD29B is here and the G5 HSI offers GPSS to those of us with older autopilots for such an inexpensive price, I'd go with the G5s. I'm a little biased because I already have the G5 ADI and really like it.
The issues I have with going with Aspen anytime in the short term are:
1) It's a pretty long-in-the-tooth product at this point with seemingly nothing in the R&D pipe w/r/t upgrades, better capabilities, etc.
2) Aspen really stings you on the upgrade prices. For example, the converter for the AP is around $2500, I believe. While they're currently giving away the SVT mod in an apparent bid to compete with Garmin, the fully upgraded Aspen costs a ton compared to the basic dual G5 setup. It's also quite a bit more to install the Aspen vs. the G5. When you compare the two at the end of the day you have to make sure to add in all of the extra costs of going with Aspen. It's not just a little bit more expensive, it's probably 2.5x more, out the door, at the end of the day.
3) Aspen is facing its first major challenge from a large mfgr since they introduced their product. Garmin hasn't really been interested in the bottom end of the market until the last year or two, and they have the resources to stand and fight for the long term. Aspen is a boutique manufacturer by comparison and will have to be lean and mean in response to Garmin's challenges. I haven't seen any hint of serious price reduction on the EFD1000 which is what will be required, in my opinion, to keep that unit market-viable (not giving away various add-ons like SVT and software AOA.) In my view a price cut across the board of at LEAST 35% will be necessary when you compare the units side by side, but my bet is Aspen won't do that.
If you have to pull the trigger today, I'd say the dual G5s are the way to go. The G5 featureset is more basic, but not by much, honestly. The Aspen will display traffic/terrain/etc. but to be perfectly frank, those are not compelling features in my view, particularly on such small displays. I fly some pretty fancy equipment at work which is capable of doing all of those things and I usually leave traffic, terrain, everything short of weather radar on my MFD only. I prefer to leave the HSI "clean" and uncluttered. At most I may want a bearing pointer which the G5 will do.
In my Twin Comanche I've offloaded almost all of the important extras like the aforementioned terrain, traffic and weather to two iPads. One's a Mini, one's an iPad Pro 9.7. Those screens are much better, and the interface far easier to manage SPIFR, than via panel interface. I have a GTN650 which I rarely interact with at all and usually leave on the "Default Nav" page -- don't really even use the Map view hardly at all, again because of the iPads. As a result the need to have this data all over your panel and all over your primary instrumentation really isn't there, in my view.
So to me the G5 makes sense. Being able to buy the HSI and GAD29B converter for under $3k is mind-blowing compared to options we've had in the last decade. That's the TOTAL price. No hidden fees. And it interfaces with the majority of legacy autopilots out there. And it's relatively simple to install. My bet is you can get dual G5s along with the GAD29B installed for under $10k. No way that will happen with the Aspen opened up with similar or greater functionality. Perhaps Aspen needs to come up with a new package of unlocks which bridge the gap between their basic VFR unit and the maxed out "Pro" package -- something that gives the user true HSI functionality and a bearing pointer, ala the G5 setup, for around $4k. That still leaves the $2500 converter they sell as an outlier but at least they'd be more competitive price-wise.
All of that said, if you can wait 8-12 months there might be some movement here that will pay off for folks who are patient. I for one am curious to see what, if anything, Aspen will do, and I'm also looking to see how the G5 performs with various older autopilots out in the field. I think there's only a small chance I'll deviate from my goal of seeing two G5s playing nicely together in my panel, but there is a chance. The real question is whether Aspen decides to keep their head in the sand or start reacting to Garmin's aggressive market maneuvering.
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