What I did....
Not necessarily the answer you are looking for, but will give you my thought process on my ELT decision. Applies to Canada only... we gotta be different here ;-)
I had already bought an ACK 121.5 MHz unit a few years back, so I installed it with the thought that I can always upgrade to the 406 MHz version in the future. ACK has a same footprint upgrade, needing only a new antenna (same remote panel).
Meanwhile, until the dust settles on the ELT issue for Canada (maybe up to another 3 years), I bought a PLB (406MHz). It is about $325 Cdn from ACS. No annual fees, and battery is good for 5 years. Advantage is that it can be deployed if you ditch (while your plane may be going under along with its ELT), and has built-in gps. Can also be used for other outdoor activities. Downside, is that it does not activate automatically.
Annual testing fee for 121.5 MHz is about $50 (incl. tax), with a battery change every 2 years (about $15). Averages to $57 per year.
Annual testing fee for 406MHz is about $140 ($125 plus tax), with battery life of 5 years. Don't know the price of the battery, but would expect it to be in the $200 range. That averages out to $180 per year.
ACK is promising a 406MHz unit for $600, and available when they will finally have jumped through all the regulatory hoops.
I also use APRS, and have a friend monitor my travels, as well as being my contact when filing a flight plan (can provide last known location if SAR calls him). $120 for the unit, plus antenna. No annual fees.
Your choice is to buy what is available now, or install a 121.5MHz unit and upgrade at a later date. Either way, you must be comfortable with your choice and level of safety (or perceived safety).
I implemented a technology mix that I am comfortable with (and legal... for the time being).