I'll tell'ya up front that I'm partial to Tascam and analog, and I own the 414mkII,..
as a very small part of my Tascam/analog "empire", (heh, heh).
With that being said,
the Fostex MR-8HD is not a bad little unit, and it's a giant,... no,... a
GIANT improvement over the original Fostex MR-8, (which I never liked).
One of the keys may be if you're heavily dependent on XLR-connected mics requiring phantom power. If that's the case, then the MR-8HD might be the better choice. The MR-8HD has 4-XLR mic inputs with onboard phantom power, while the 414mkII has 2-XLR mic inputs with no phantom power. However, I've heard some dicey things about the quality of the MR-8's preamps, and hopefully the MR-8HD would have better preamps than the MR-8(std), but that's speculation and I've not heard any evidence that the preamps in the "HD" are improved over the "std".
The MR-8HD has no "input-side" mixing capability,... so if that's anything to'ya, it might be better to favor the Tascam. The MR-8HD has what I call "inputs-to-tracks" architecture, but the Tascam 414mkII's mixer has the capability of mixing up to 8 inputs on the way in to the recorder, as well as the requisite mixing on the way out.
The learning curve on the MR-8HD would be considerably steeper than the 414mkII, which would be more or less intuitive to operate.
Plus, with the 414mkII @ $249 and the MR-8HD @ $399, I'd hardly say the difference in price is insignificant.
Cassette is a simple and convenient removable media, that's almost endlessly archivable. I personally have several hundred home recorded music cassettes in the "archives".
On the other hand, the MR-8HD has an internal hard drive and is somewhat dependent on the ol'puter for data transfers. Some people love the concept of music files being tied intrinsically to their 'puters, and to other people that idea is distasteful.
As someone who just "lost" an 80Gb hard drive to unexplainable "corruption" after hitting the power button when his 'puter hung up, I'd feel less than secure tying my home recordings intrinsically to the 'puter. The only thing that saved my bacon, was that I had another 'puter in another room which had a duplicate copy of all my "master" mixes on it,... some 340 WAV files and 9Gb of data,... mixes that go back 7 years!!!... Saved by a little forethought on my part!! That may be relevant to you, or not, but it's something to consider. I'd have
hated to lose 340 mixes & have to redo'em from scratch! (I did lose 2 years of irreplaceable family photos, though!! Kids only grow up once, you know!)
Point: Anything with a hard drive is subject to failure, corruption, or the sudden and unexpected loss of valuable data. The MR-8HD is no exception.
Lastly, I don't think anyone can predict the ongoing availability of Type II/Chrome cassette tapes, but I've taken to buying them when I can, as "future-proofing" my HUGE investment in analog cassette Portastudios.
You'll probably get as many opinions on this, as people you ask. In general, there's a "newer is better,... hard drive is the way to go,... forget cassette" mentality out there, as proven by the home recording industry itself abandoning analog, but I'm here to say that a 414mkII analog cassette Portastudio is still a viable and relevant way to record music. It doesn't have to be all about 'puters, does it? Also, the obvious fact that the 414mkII sounds good and is easy to use for the rank novice is a great selling point, in this techno-crazy society we live in. Anyway, although they cannot be purchased brand new any more, the 424mkIII represents a significant uplift in features and capability over the 414mkII, and may be worth considering.
Maybe glossed over until now, is that the 414mkII is a 4-track, and the MR-8HD is 8-tracks, and you have to consider your present and future needs to determine just how important that "track count" is to you.
I know you referred to using an external mixer if you needed to implement your mics that require phantom power, so the issue of built-in phantom power is not a deal-breaker,... which is another reason I'd stick with the Tascam.
The bottom line for me,... is that I have (3) 414mII's, and not a single MR-8HD, although I could well afford an MR-8HD if I wanted one. That doesn't prove anything, necessarily, but I'd never recommend anyone buys anything that I'd not buy myself. Take that statement for what it's worth!
Good luck!!
PS: If you want at least a "ballpark" estimation on the fidelity of the Tascam Portastudio, go check my soundclick page, (linked off my username). Correct me if I'm wrong, but I don't hear any hiss or drag on that page!
