The plans I had for a vor based nav are now out the window. My thoughts are that there is no vor as accurate as a Loran or GPS, expecially for a vor approach. Localizer/glideslope would be nice, but I don't fly a 170 (or any other single engined airplane) in weather so poor that a non-precision approach and/or circling minimums isn't completely adequate.
My 206 had Narco Com 120's and Nav 122 and 121 and ADF-141 and 150A TXDR. They always worked flawlessly (installed for over 12 years) and the only failure was fixed by a local shop with a plastic tuning-gear change and a recalibration.
When Narco decided to quit certifying every mom-and-pop shop in the world and go to factory and/or "master" repair stations, I was at first disappointed. I wrote them and complained. I got a reasonable, if not exactly believable, response. It said they'd had so many problems with small shops performing poor repairs they'd decided to get a closer/better handle on who would be authorized to perform maintenance. They promised fast turnaround. I wondered.
Two years ago, I became convinced by PM Engineering that my Narco 810 was the guilty party to a cold-weather transmision problem. (Carrier only, no modulation.) So I sent the radio to Narco and asked for a quick-turn since it was my only installed comm. (My handheld is my backup.)
Within 24 hours they called me and said they couldn't duplicate the problem even by subjecting the unit to the freezer. They blamed my PM Engineering intercom. I told them I didn't believe it, because PM 's intercom goes into fail-safe mode when it fails....it basically removes itself from the system when it fails. I know. PM Engineering said so. I'd already discussed this problem with them, and they said the problem could ONLY be Narco's radio.
Narco just said "sorry, can't duplicate the problem" and sent it back to me overnight with a bill for $120.
When I got it in my hands, I saw the invoice also stated the radio now had a 1-year warranty because it'd been "repaired" at the factory.
I installed it, and same old problem.
I removed my PM 1000+ and sent it to PM, and they called the next week and confirmed that their internal microphone relay was at fault. They fixed it for $48 and shipped it back to me for another $12. No extended warranty. PM's bad advice had cost me a week and $120 wasted (except for the nice new warranty on the Narco.)
My bottom line: I have faith in my stand alone Narco radios. They've done well by me. I believe they have made a good business decision to let all the other dogs in the GPS fight go at each other and confine their own efforts at basic, inexpensive, reliable radios. It's what they do best, and their factory maintenance is top notch and fast turnaround.
The local avionics shops don't like them because they are not high-dollar earners for them, and they make no money on repairs with factory repair schemes. But think about this: Modern avionics are not repaired in the same fashion as the old stuff used to be. Modern radios are "depot" style repairs in that they have entire circuit boards and modules that get replaced. If your local shop took your radio in for repair, they'd have to diagnose and advise you they need to "order parts, be here next week". Then they'd install the replacement board, and bill you for several hours work.
Narco's system works faster for the same, infrequent failures, and end up costing less money. The only drawback I see is the lack of an off-the-shelf loaner radio from the local shop. (But Narco will loan/rent a replacement radio if you request it.)
For those who like the King KY97 series, you might find it helpful to know that the ICOM A200 series is the exact same radio with a different name-plate for less money. The difference that might be of use to you is that your local avionics shop might be more likely to be King (or Honeywell actually) authorized repair station, and your Icom might have to be shipped back to the factory for repair just because of the name plate. It will depend upon whether or not the local shop is authorized (has purchased the manuals, parts, etc.) for both "brand names".
P.S. Another feature I like about Narco's stand alone radios is they do not require an audio amplifier. They have built in amplifiers capable of driving speakers. While an audio switching panel is nice, it's not required, which can save you $500 or more. Not so with most other brands.
I just added a Narco COM 120 as a second COM radio...got it for $300 * and it works just fine. I just installed a KX-155 with KI-209 indicator for full ILS capability...but have to say I would not opt for this system if I had it to do over again. I would go with the Narco MK12D and mating indicator. Why? Cost of the Narco system is several hundred less and the indicator is much shorter making for an easier panel intallation in several areas where the long KI indicators foul up on stuff. I like Narco because they concentrate on offering a decent product for the lower end (me) of the GA market. Good solid avionics without all the bells and whistles. King, Garmin/UPS, and the other makers of the fancy MFD units are only interested in the upper half of the GA market. I like Narco because they cater to the little guys who still know the value of a dollar and don't have too many of those dollars to throw at "wonder boxes". That said, VAL and Mitchell are also good companies that support the little guys.